标签：#nextjs

I did not choose DeepSeek because I think GPT-4 is bad. I chose it because I was building a free app, and free apps teach you what actually matters pretty fast. The question was simple: how do I keep sessions cheap enough that people can practice a lot without me lighting money on fire? The answer pushed me toward DeepSeek-V3 (and later R1 for specific tasks). The real constraint was volume The app is a conversation practice tool. People come in to rehearse hard talks, not to admire the model. A single practice session runs 8-15 turns. Each turn is roughly 300-600 tokens in, 100-300 out. Multiply that by five sessions a week per active user and the costs start compounding. Here is what the math looked like when I was choosing (mid-2026 pricing): Model Input cost (per 1M tokens) Output cost (per 1M tokens) Cost per 10-turn session (est.) GPT-4o $2.50 $10.00 ~$0.04-0.06 GPT-4 Turbo $10.00 $30.00 ~$0.12-0.18 DeepSeek-V3 $0.27 $1.10 ~$0.004-0.007 DeepSeek-R1 $0.55 $2.19 ~$0.008-0.012 At scale, the difference between $0.005 and $0.05 per session is the difference between running a free product and needing a paywall after three conversations. I wanted people to come back daily without hitting a wall. What DeepSeek handled well It stayed in character for 10-15 turns. It pushed back when the user got vague. It followed persona heuristics (numbered if/then rules in the system prompt) about as reliably as GPT-4o did for our use case. For salary negotiation rehearsal, the model needs to say "that's not in the budget" and hold that position for three more turns while the user tries different approaches. DeepSeek-V3 did this. Not perfectly, but reliably enough that sessions felt real. It also made the app easier to run as a free product. People can try, fail, reset, and try again without me worrying about per-session cost. Where GPT-4 was still better GPT-4 (and 4o) is smoother with nuanced emotional wording. When a conversation gets subtle, loaded with subtext, or requires pick

As a solo developer I wanted a fast, mobile-friendly interactive map for Palworld that didn't bury me in ads. The result is Pindrop , and here are a few of the technical decisions behind it. Rendering 1000+ markers without jank The interactive map uses Leaflet with a custom marker-clustering layer. Markers are served as static JSON from the edge and hydrated client-side, so the first paint is server-rendered and the heavy marker work happens after. A breeding calculator as a pure function Palworld's breeding combos are deterministic, so the breeding calculator is just a lookup over a precomputed table rather than a backend call. That keeps it instant and fully cacheable. Stack Next.js (App Router) for SSR + static generation Leaflet for the map layer Supabase for the small amount of dynamic data Vercel for hosting and edge caching If you play Palworld, the guides section collects the breeding, location and boss notes I kept losing track of. Feedback from other devs welcome — especially on the clustering approach.

Hi everyone 👋 I'm a Full Stack Developer with experience in JavaScript, React.js, Next.js, Node.js, Express.js, MongoDB, and WordPress development. Over the last few years, I have worked on multiple projects ranging from company websites to full-stack web applications. In this article, I want to share my experience transitioning from the traditional MERN stack to Next.js and why it has become my preferred framework for modern web development. Why I Started with MERN Stack The MERN stack was my first choice because it allowed me to build complete applications using JavaScript. Technologies MongoDB Express.js React.js Node.js Benefits ✅ Single language across frontend and backend ✅ Huge ecosystem ✅ Fast development ✅ Easy API integration Challenges I Faced As projects became larger, I started facing issues like: SEO limitations Performance optimization Routing complexity Code organization Server-side rendering requirements This is where Next.js entered the picture. Why I Switched to Next.js Next.js provides several powerful features out of the box. Server-Side Rendering (SSR) Pages can be rendered on the server which improves SEO and initial page load performance. 2.** Static Site Generation (SSG)** Perfect for blogs, landing pages, and marketing websites. 3.** App Router** The new App Router makes routing cleaner and more scalable. Server Components Less JavaScript is sent to the browser, improving performance. Better Developer Experience Features like: File-based routing Built-in image optimization Middleware API routes make development faster and cleaner. My Current Tech Stack Frontend Next.js React.js TypeScript Tailwind CSS Backend Node.js Express.js MongoDB Tools Git & GitHub Postman Vercel Contentful CMS What I Learned The biggest lesson I learned is: Focus on solving real business problems instead of chasing every new technology. Frameworks will change, but understanding JavaScript fundamentals, APIs, databases, authentication, and system design will always be

📝 Originally published in Japanese on Zenn. This is the English version. Canonical: https://zenn.dev/uya0526_design/articles/satellite2_haiku-coaching 📚 This is satellite article #2 in my "Read-Aloud Speed Meter dev log" series. For the whole picture, see the main article ; for the AmiVoice integration, see satellite #1 . Where This Sits This article covers the part of the read-aloud speed meter that hands the measured numbers to Claude Haiku to generate coaching as "one compliment + one improvement." Many articles that use generative AI just dump it on the model: "here's the recognized text, evaluate it nicely." This article is the opposite. Don't let the LLM do the math. All computation and rule-based decisions are settled in code, and Haiku only does the wording. I'll go through how I designed this "two-stage" split, and which swamps I sank into during implementation. Four things: Why "code does the math, Haiku only does the wording" (the role-split design) The finalized prompt, and the messages / system / cache_control implementation First-hand findings: the prompt cache that didn't work The moment real data slapped me with "written in the prompt ≠ obeyed" 💡 I'm an ex-Java engineer learning TypeScript in public, so I drop in Java comparisons. Why Not Let Haiku Do the "Math"? Up front: Haiku is more than enough for feedback generation — in fact, you can shape the task into something Haiku is good at. The key is the role split. I settle all the metric computation (speaking speed, stagnation rate, threshold decisions) entirely in code. So by the time it reaches Haiku, it's already settled facts like this (below is from running labelMetrics on a real measurement — reading the Heike sample during development; stagnationRate is a number for percentage display): { "pureSpeakingSpeed" : 322 , "pureSpeakingSpeedEvaluation" : "slightly fast" , "stagnationRate" : 0 , "stagnationRateEvaluation" : "few" } Haiku's only job is to translate these numbers and labels into warm, c

📝 Originally published in Japanese on Zenn. This is the English version. Canonical: https://zenn.dev/uya0526_design/articles/satellite1_amivoice-bff 📚 This is satellite article #1 in my "Read-Aloud Speed Meter dev log" series. For the whole picture, see the main article . Where This Sits In the read-aloud speed meter app, this article covers the part that sends browser-recorded audio to the AmiVoice API to get back recognized text plus timestamps. The theme is calling an external API without exposing your API key to the browser — in other words, implementing a BFF (Backend for Frontend). The main article only touched the highlights, so here I go down to a level you can reproduce yourself. Specifically, four things: Why you must not call AmiVoice directly from the browser (why a BFF is needed) AmiVoice's synchronous HTTP auth, parameters, and multipart order Why the browser's MediaRecorder output (WebM/Opus) passes through as-is Reshaping the raw JSON with a pure-function mapper and testing it with fixtures 💡 I'm an ex-Java engineer learning TypeScript in public, so I drop in comparisons to Java here and there. Why a BFF Is Needed Using the AmiVoice API requires an API key. And that key must never appear in browser-side code. Frontend JavaScript is fully inspectable by the user, so writing the key there leaks it instantly. So I insert a relay that holds the key. [Browser] ──audio Blob──▶ [Next.js API Route (BFF / holds key)] ──▶ [AmiVoice API] record / display audio field reshape into u / d / a speech → text The browser only calls my own API Route ( /api/recognize ), and that Route attaches the key server-side and forwards to AmiVoice. The key is just read from process.env and never ends up in the bundle shipped to the browser. ☕ Java comparison: This is the same as a Spring @RestController reading an external API key from application.yml (env vars) and relaying without showing it to the client. Think "a thin Servlet that hides the secret and relays an external API."

📝 Originally published in Japanese on Zenn. This is the English version. Canonical: https://zenn.dev/uya0526_design/articles/main_article_reading-speed-meter Introduction — What I Built I built a web app that lets you read a Japanese passage aloud, measures your speed and fluency, and has an AI coach return a one-line piece of feedback. 🌐 Demo: https://reading-speed-meter.vercel.app/ 📦 Repository: https://github.com/uya0526-design/reading-speed-meter The flow is simple. You read a passage aloud into the mic (up to 10 seconds) while looking at the script — I prepared the opening lines of two Japanese classics, The Tale of the Heike and Hōjōki — and when you press "Measure," : AmiVoice API recognizes the audio, the code computes your pure speaking speed (characters/min) and stagnation rate from that result, and Claude Haiku returns coaching as "one compliment + one improvement." (Measurement starts on a button press after recording — it never runs automatically.) This article aims to be a single, self-contained piece covering the whole picture, the design decisions, and the reproduction steps . 💡 Where this sits in my journey I'm an ex-Java engineer learning TypeScript and Python in public. This was my first project where I deliberately adopted "AI-collaborative development" as a clear mode. Throughout, I'll drop in comparisons to Java — hopefully useful for anyone coming from a similar background. What You'll Get From This Article How to design evaluation logic that fully exploits the per-word timestamps AmiVoice returns How to build a BFF (Backend for Frontend) so API keys never reach the browser A "two-stage" design where code does the math and Claude Haiku only does the wording First-hand findings you only learn by verifying — e.g., "I thought I'd optimized it, but it wasn't actually working" I include concrete endpoints, parameters, and environment variables so you can reproduce it yourself. My Learning Style (AI Transparency) 💡 Learning companions & how this art

A few days ago I published a post about the three-layer auth model and the invoice incident that made...

Running 23 European e-commerce shops on Payload CMS v3 taught me that some things simply don't exist yet. So I built them. Background I maintain a multi-clone e-commerce infrastructure — 23 Next.js + Payload CMS v3 shops deployed across Europe, each on its own subdomain and language. Think fr.myshop.com , de.myshop.com , sk.myshop.com ... all running on the same codebase with country-specific patches. While building this, I kept running into two missing pieces that no one had published for Payload v3: A customer reviews system with admin moderation and Google star ratings Complete Schema.org JSON-LD for Google rich snippets (Product, BreadcrumbList, ItemList, AggregateRating) Both are now published on npm. Here's what I built, the bugs I hit, and how I solved them. Part 1 — The Reviews Plugin What didn't exist Search npm for payload reviews or payload ratings — you'll find nothing for v3. The official plugin ecosystem covers SEO, forms, redirects, Stripe... but not customer reviews. Building the collection The reviews collection itself is straightforward — relationship to products , rating (1-5), status select (pending/approved/rejected), author fields. The tricky parts came later. Access control gotcha: Payload v3 uses a roles array, not a role string. This breaks if you copy v2 patterns: // ❌ Wrong — always returns false update : ({ req }) => req . user ?. role === ' admin ' , // ✅ Correct for v3 update : ({ req }) => req . user ?. roles ?. includes ( ' admin ' ), Prevent self-verification: Users can POST any field on create: () => true collections. Lock verified in a beforeChange hook: hooks : { beforeChange : [ ({ data }) => { if ( ! data . status ) data . status = ' pending ' data . verified = false // admin-only, always reset on create return data }, ], }, Email protection: read: () => true on the collection exposes authorEmail in the public API. Add field-level access: { name : ' authorEmail ' , type : ' email ' , access : { read : ({ req }) => req . user ?.

A data export endpoint dumps system diagnostics when it hits an invalid field. Feed it garbage, read the debug output, grab the flag. A data export feature lets you pick which profile fields to download. The UI only offers valid fields through checkboxes, so everything looks locked down. But the API behind it accepts arbitrary field names -- send it one it doesn't recognize, and instead of a clean error, it dumps full system diagnostics including internal feature flags. That's where the flag is. You'll bypass the frontend, hit the endpoint directly, and read what comes back. Lab setup Start the lab: npx create-oss-store@latest Or with Docker (no Node.js required): docker run -p 3000:3000 leogra/oss-oopssec-store The app runs at http://localhost:3000 . What you're targeting The app has a profile page at /profile with a Data Export tab. It lets users download their own data in JSON or CSV by selecting fields through checkboxes ( User ID , Email , Role , Address ID ) and clicking "Export Data". The UI looks safe -- you can only pick from a fixed set of valid fields, so there's no way to submit an invalid one through the browser. But that's just client-side validation. The endpoint behind it is POST /api/user/export , and it accepts a JSON body with two parameters: { "format" : "json" , "fields" : [ "id" , "email" , "role" ] } The fields value is an array of strings. The API checks each field against an allowlist. Valid fields? You get your data back. Invalid fields? The API throws an error -- and that error says way too much. Step-by-step exploitation 1. Log in You need an authenticated session. Use one of the seeded accounts: Email: alice@example.com Password: iloveduck Log in through the UI at /login , or grab a session cookie via curl: curl -c cookies.txt -X POST http://localhost:3000/api/auth/login \ -H "Content-Type: application/json" \ -d '{"email":"alice@example.com","password":"iloveduck"}' 2. Explore the Data Export tab Go to /profile and click the Data Export

I Built a 4-Sided Plot Area Calculator with 2D & 3D Visualization Most online plot calculators only work for simple rectangular plots. However, many real-world properties have four sides with different measurements, making area estimation much more difficult. That's why I built a 4-Sided Plot Area Calculator that allows users to enter the North, South, East, and West dimensions and instantly calculate the approximate plot area. 🔗 https://www.premiumconverters.com/plot-area-calculator Features 📐 Supports irregular 4-sided plots 🏠 Calculates area in Marla, Kanal, Acres, and more 🖼️ Interactive 2D top-down visualization 🏗️ Isometric 3D plot rendering 📏 Feet & inches input support 📱 Mobile-friendly experience Why I Built It In many countries, especially in South Asia, property dimensions are often recorded as side measurements rather than perfect geometric shapes. Existing tools rarely address this use case properly. I wanted to create a simple solution that homeowners, buyers, real estate professionals, and developers could use without needing complex surveying software. The Result The calculator transforms four side lengths into a practical estimate while providing visual feedback that helps users better understand their property's shape. Building tools that solve real-world problems is one of the most rewarding parts of software engineering. Have you ever built a niche tool that unexpectedly helped thousands of users?

La trahison du chiffre Vendredi 15 mai, 16 h 13. L'alerte Sentry remonte sur le téléphone. La première réinscrite Phase 1 attend devant l'écran de paiement, son nom est en haut de mon onglet. Je pose la canette, je rouvre l'écran. La tasse à tête de Françoise, sur le poste d'à côté, capte un reflet jaune que je remarque sans le regarder. La stack trace tient en plein écran. Le stack trace s'ouvre, neuf champs sur dix à null , et un chiffre que je n'ai pas vu venir. type = "StripeConnectionError" message = "An error occurred with our connection to Stripe." code = null statusCode = null requestId = null duration = 9 ms Neuf millisecondes. Sur une route Vercel en région Paris, un DNS résout en quarante millisecondes, un handshake TLS coûte cent à deux cents. Neuf millisecondes, ce n'est pas un appel réseau qui a échoué. C'est un appel réseau qui n'a jamais eu lieu. Le SDK n'est pas arrivé jusqu'à la fibre. L'instinct propose immédiatement trois patchs. Timeout serverless Vercel — j'ajoute maxDuration , je redéploie. Clé révoquée — je vais la rouler. Compte Stripe restreint après le passage en mode live — j'ouvre un ticket support. Ces trois hypothèses sont plausibles. Aucune des trois n'est falsifiable par le symptôme seul, et c'est précisément ce qui les rend dangereuses : chacune ouvre un cycle de quinze à trente minutes avec rollback à la fin si elle se trompe. Multiplié par trois, on tient une demi-journée perdue avec la cliente toujours en train de cliquer. Je n'ai pas le temps. Une réinscrite attend. Quatre tests, dans l'ordre Je connais la classe d'incident — « preview marche, prod casse » , ou son symétrique. La règle, pour cette classe, c'est qu'on ne corrige rien tant qu'on n'a pas discriminé les couches. Quatre tests, exécutés dans l'ordre. Chacun élimine une famille d'hypothèses, pas une hypothèse isolée. Et chacun est conçu pour réfuter ce qu'il vient interroger — parce qu'un test qui cherche à confirmer trouve toujours, par sélection, ce qu'il cherche. Te

The number that lied Friday May 15, 4:13 PM. The Sentry alert pings on my phone. The first Phase 1 re-enrolling student waits in front of the payment screen, her name at the top of my tab. I put down the can, I reopen the screen. The mug with Françoise's face on it, on the desk next door, catches a yellow reflection I notice without looking at. The stack trace fills the screen. The stack trace opens, nine fields out of ten at null , and a number I didn't see coming. type = "StripeConnectionError" message = "An error occurred with our connection to Stripe." code = null statusCode = null requestId = null duration = 9 ms Nine milliseconds. On a Vercel route in Paris region, DNS resolves in forty ms, a TLS handshake costs one to two hundred. Nine milliseconds isn't a network call that failed. It's a network call that never happened. The SDK didn't reach the wire. Instinct immediately offers three patches. Vercel serverless timeout — I add maxDuration , redeploy. Revoked key — I'll rotate it. Stripe account restricted after the live switch — I open a support ticket. These three hypotheses are plausible. None of the three is falsifiable from the symptom alone, and that's precisely what makes them dangerous: each opens a fifteen-to-thirty-minute cycle with rollback at the end if it's wrong. Multiplied by three, half a day lost with the customer still clicking. I don't have time. A student is waiting. Four tests, in order I know the incident class — "preview works, prod breaks" , or its mirror. The rule for this class is that you fix nothing until you've discriminated the layers. Four tests, executed in order. Each eliminates a family of hypotheses, not an isolated hypothesis. And each is designed to refute what it interrogates — because a test that seeks to confirm always finds, by selection, what it's looking for. Test 1 — reproduce in the witness environment. I rerun the same funnel in preview, with the sk_test_ key. Checkout opens in three hundred fourteen milliseconds,

Supply chain security is terrifying right now. With new vulnerabilities popping up daily and governments mandating compliance (like the EU CRA and US Executive Orders), I realized my open-source projects were completely flying blind. I needed a Software Bill of Materials (SBOM) to track exactly what dependencies I was shipping. But every tool I found was either a massive enterprise platform or a clunky CLI tool that took forever to set up. So, I built my own. It's called Deptic . 🏗️ The Architecture I wanted the developer experience to be completely frictionless: you paste a GitHub URL, and it instantly spits out a compliant SBOM and highlights any critical CVEs. Here is the tech stack I went with: Next.js 14 (App Router): For a lightning-fast React frontend and seamless API routes. Go (Golang): The backend scanning engine. Go's incredible concurrency allows it to parse massive dependency trees in milliseconds. Supabase: For database management and instant authentication. Tailwind CSS: Because writing raw CSS is pain. 🧩 The Hardest Part: Dependency Resolution Building the UI was easy. Parsing package.json or go.mod files? Also easy. The hardest part was recursively walking down the dependency tree to find transitive dependencies (the dependencies of your dependencies). I had to write custom parsers that could speak to the NPM registry, PyPI, and Maven Central simultaneously to map out the entire tree and cross-reference them with global CVE databases in real-time. 🚀 The Result What started as a weekend script turned into a full platform. Deptic now supports: Instant scanning of public GitHub repos. Generating perfectly compliant CycloneDX (1.5) and SPDX (2.3) JSON files. Live CVE vulnerability detection. Try it out! If you want to see exactly what dependencies are hiding in your codebase, you can run a free scan here: 👉 deptic.netlify.app It's completely free for developers. I would love to get your brutal feedback on the UI, the scanning speed, or any feature reque

A few weeks ago I shipped a feature I'd been putting off because it felt like it needed a backend: subscribable calendar feeds. "Add this holiday to Google Calendar." "Subscribe to all your country's public holidays so they show up in Apple Calendar forever." Every calendar competitor has this. My site had none. The catch: the whole thing is a static export — next build produces a folder of HTML/CSS/JS that I drop on Cloudflare Pages. No server, no API routes at request time, no ISR. So how do you serve a .ics feed that a calendar app polls every few hours? Turns out you don't need a server at all. Here's the approach, the RFC 5545 gotchas that bit me, and the parts I'd tell my past self. The "aha": a feed is just a file A .ics subscription feed is not a live API. It's a static text file that calendar clients re-fetch on a schedule. So for a static site, the idiomatic move is a post-build emitter : after next build , run a Node script that walks your data and writes assets straight into out/ . # scripts/deploy.sh npx next build node scripts/emit-feeds.mjs # writes .ics + .json into out/ That's the entire architecture. The emitter reads the same JSON the pages render from, so the feeds can never drift out of sync with the site — there's one source of truth. It emits: a per-year feed ( holidays-de-2026.ics ) a per-holiday feed (one event, for the "download this day" button) an all-years subscription feed (the one you point webcal:// at) and, almost for free in the same loop, a JSON API under out/api/ No new pages, no new routes. Just files. RFC 5545: all-day events are sneakier than they look I assumed an all-day event on Jan 1 would be DTSTART:20260101 , DTEND:20260101 . Wrong. DTEND is exclusive. A one-day all-day event ends on Jan 2 : BEGIN:VEVENT UID:de-2026-neujahr@calendana.com DTSTAMP:20260614T101500Z DTSTART;VALUE=DATE:20260101 DTEND;VALUE=DATE:20260102 SUMMARY:Neujahr TRANSP:TRANSPARENT CATEGORIES:Holiday END:VEVENT Get this wrong and some clients render a ze

I Cut My Next.js + Supabase App Load Time by 73% - Here Are the 5 Techniques That Actually Worked Last month, our SaaS dashboard was embarrassingly slow . 4.2 seconds to load the main page. Users were complaining. Conversion rates were tanking. Today? 1.1 seconds . 73% faster. Here's exactly what worked (and what didn't). The Problem: Death by a Thousand Database Calls Our dashboard showed user projects, team members, recent activity, and notifications. Sounds simple, right? Wrong. Each component was making its own database calls. The projects list fetched projects, then made separate calls for each project's stats. The activity feed loaded events, then fetched user details for each event. Classic N+1 query problem, but worse. Technique #1: Strategic Data Fetching Consolidation Before: 47 database calls to load the dashboard After: 3 database calls The fix wasn't fancy. We consolidated related data into single queries using Supabase's nested select syntax: // ❌ Before: Multiple separate calls const projects = await supabase . from ( ' projects ' ). select ( ' * ' ) const stats = await Promise . all ( projects . map ( p => supabase . from ( ' project_stats ' ). select ( ' * ' ). eq ( ' project_id ' , p . id )) ) // ✅ After: Single consolidated call const projects = await supabase . from ( ' projects ' ) . select ( ` *, project_stats(*), team_members(count), recent_activity:activities(*, user:users(name, avatar_url)) ` ) . limit ( 10 ) Result: Dashboard load time dropped from 4.2s to 2.8s (33% improvement) Technique #2: Aggressive Caching with Smart Invalidation Most dashboard data doesn't change every second. We implemented a three-tier caching strategy: // Static data: Cache indefinitely const categories = await supabase . from ( ' categories ' ) . select ( ' * ' ) . cache ({ revalidate : false }) // Semi-static data: Cache with revalidation const userProjects = await supabase . from ( ' projects ' ) . select ( ' * ' ) . eq ( ' user_id ' , userId ) . cache ({ revali

Next.js + Supabase Performance Optimization: From Slow to Lightning Fast Last month, I optimized a Next.js + Supabase application that was frustratingly slow. Initial page load took 4.2 seconds, Lighthouse performance score was 62, and users were complaining. After applying these optimization techniques, we achieved: 70% faster load times (4.2s → 1.3s) Lighthouse score of 96 (up from 62) LCP improved by 65% (3.8s → 1.3s) 50% reduction in database queries Here's exactly how we did it. The Starting Point: Measuring Performance Before optimizing anything, we measured current performance using: Lighthouse (Chrome DevTools): Performance: 62 First Contentful Paint (FCP): 2.1s Largest Contentful Paint (LCP): 3.8s Total Blocking Time (TBT): 420ms Cumulative Layout Shift (CLS): 0.18 Real User Monitoring: Average page load: 4.2s Time to Interactive: 5.1s Database query time: 850ms average The Problems: Unoptimized database queries No caching strategy Large JavaScript bundles Unoptimized images Blocking render paths Too many client-side fetches Let's fix each one. 1. Database Query Optimization Problem: N+1 Queries The biggest performance killer was N+1 queries. We were fetching posts, then fetching the author for each post individually. // ❌ Bad: N+1 queries (1 + N database calls) async function getPosts () { const { data : posts } = await supabase . from ( ' posts ' ) . select ( ' id, title, author_id ' ) // Fetching author for each post = N queries const postsWithAuthors = await Promise . all ( posts . map ( async ( post ) => { const { data : author } = await supabase . from ( ' users ' ) . select ( ' name, avatar ' ) . eq ( ' id ' , post . author_id ) . single () return { ... post , author } }) ) return postsWithAuthors } Impact: 50 posts = 51 database queries (850ms total) Solution: Use Joins // ✅ Good: Single query with join (1 database call) async function getPosts () { const { data : posts } = await supabase . from ( ' posts ' ) . select ( ` id, title, author:users(nam

7 Things I Wish I Knew Before Scaling Next.js + Supabase to 100K Users Six months ago, we launched our SaaS with Next.js and Supabase. The stack was perfect for our MVP: fast development, great DX, and it just worked. Then we hit 10K users. Then 50K. Then 100K. Everything that worked beautifully at small scale started breaking. Database queries that took 50ms now took 5 seconds. Our Supabase bill went from $25/month to $800/month. Users complained about slow page loads. Here's what I wish someone had told me before we started. 1. RLS Policies Are Not Optional (Even in Development) We skipped RLS in development. "We'll add it before launch," we said. Launch day came. We enabled RLS on all tables. The app broke in 47 different places. Queries that worked suddenly returned empty arrays. Inserts failed with permission errors. We spent 12 hours fixing RLS policies while users waited. What I'd do differently: Enable RLS from day one. Write policies as you create tables: CREATE TABLE posts ( id UUID PRIMARY KEY DEFAULT uuid_generate_v4 (), title TEXT NOT NULL , user_id UUID REFERENCES auth . users ( id ) ); -- Enable RLS immediately ALTER TABLE posts ENABLE ROW LEVEL SECURITY ; -- Write policies now, not later CREATE POLICY "Users can view own posts" ON posts FOR SELECT USING ( auth . uid () = user_id ); Test with RLS enabled. If it works in development, it'll work in production. 2. Database Indexes Are Not Premature Optimization "We'll add indexes when we need them." We needed them on day 3. Our posts feed query went from 50ms to 8 seconds as we hit 10K posts. Users complained. We scrambled to add indexes during peak traffic. The query: const { data } = await supabase . from ( ' posts ' ) . select ( ' *, profiles(*) ' ) . eq ( ' published ' , true ) . order ( ' created_at ' , { ascending : false }) . limit ( 20 ) The fix: CREATE INDEX posts_published_created_at_idx ON posts ( published , created_at DESC ) WHERE published = true ; Query time dropped to 12ms. What I'd do di

For years, whenever I needed to merge two PDFs or compress a file to upload to a government portal, I would Google "compress PDF", click the first result, and inevitably hit a paywall. "You have reached your 2 free files per day limit." Worse, I was uploading sensitive documents—tax returns, medical records, and NDAs—to random servers in God-knows-where just to strip out some heavy images. I decided to build an alternative. I wanted it to be 100% free, have absolutely no daily limits, and most importantly: zero server uploads . Here is how we built PDF Pro using Next.js and WebAssembly to process PDFs entirely natively inside the user's browser. The Architecture: Why WebAssembly? Traditional PDF tools (like Smallpdf or iLovePDF) use a monolithic server architecture. You upload your file to their AWS bucket, their backend runs a Python or C++ script (usually using Ghostscript or a proprietary library) to manipulate the PDF, and then you download the processed file. This architecture is expensive (high bandwidth and compute costs) and creates a massive privacy liability. By compiling a C++ PDF manipulation library down to WebAssembly (WASM) , we inverted the architecture. 1. The Build Process We took pdf-lib and custom C++ compression algorithms and compiled them to a lightweight .wasm binary. When a user visits PDF Pro Compress , their browser downloads the ~2MB WASM file once and caches it. 2. Client-Side Processing When you drag and drop a 50MB PDF into the UI, it never hits our server. Instead, the browser's JavaScript engine passes a Pointer to the file data directly into the WebAssembly memory buffer. The WASM module executes native C++ speeds directly on your local CPU to compress or merge the document. Performance Benchmarks Because there is zero upload and zero download time, the performance metrics are staggering: 10MB PDF Compression (Cloud): ~15 seconds (Upload) + 4 seconds (Process) + 5 seconds (Download) = 24 seconds . 10MB PDF Compression (PDF Pro WASM)

I automated my Gumroad product screenshots with Playwright I recently started packaging a few small frontend projects as digital products, and one surprisingly annoying part was preparing product screenshots. Manual screenshots quickly became messy: different browser sizes inconsistent cropping blurry images mobile screenshots were easy to get wrong Gumroad needed a square thumbnail every update meant taking screenshots again So I built a small local screenshot workflow with Next.js and Playwright. The workflow captures: desktop screenshots mobile screenshots square thumbnail images consistent PNG outputs route status checks basic console error reporting basic horizontal overflow checks The basic command flow is: npm run build npm run start npm run screenshots The script reads a simple config file, opens the configured local routes, captures each screenshot with consistent viewport settings, and exports the images into a predictable folder. For example: screenshots/gumroad/ landing.png dashboard.png template-preview.png mobile-preview.png thumbnail.png I found this especially useful when preparing Gumroad product galleries, because I could regenerate all product images after every UI change instead of taking screenshots manually. This is not a hosted screenshot service. It is just a local source-code workflow for people who want to generate product screenshots from their own Next.js pages. I packaged the workflow as a small Gumroad product here: https://remix410.gumroad.com/l/screenshot-automation-kit Curious how other developers handle product screenshots. Do you take them manually, use Playwright/Puppeteer, or use a design tool workflow?

Serverless functions have a time limit. Vercel gives you 60 seconds on Pro. None of that is enough to send a welcome email sequence, process an uploaded CSV, or run any workflow with multiple external API calls. Inngest solves this by turning your Next.js API routes into reliable, retryable, observable background jobs — without Redis, without a worker process, without any separate queue infrastructure. Read the full guide with all code examples at stacknotice.com How It Works You define functions that run in response to events . When an event fires, Inngest calls your function via HTTP. If the function fails, Inngest retries it. If the function has multiple steps, Inngest checkpoints each step so a failure halfway through doesn't restart from scratch. Setup npm install inngest // lib/inngest/client.ts import { Inngest } from ' inngest ' export const inngest = new Inngest ({ id : ' my-app ' }) // app/api/inngest/route.ts import { serve } from ' inngest/next ' import { inngest } from ' @/lib/inngest/client ' import { welcomeSequence } from ' @/lib/inngest/functions/welcome ' export const { GET , POST , PUT } = serve ({ client : inngest , functions : [ welcomeSequence ], }) Welcome Email Sequence export const welcomeSequence = inngest . createFunction ( { id : ' welcome-email-sequence ' , retries : 3 }, { event : ' user/signed-up ' }, async ({ event , step }) => { const { userId , email , name } = event . data // Each step is independently retried await step . run ( ' send-welcome-email ' , async () => { await resend . emails . send ({ from : ' hello@yourapp.com ' , to : email , subject : `Welcome, ${ name } !` , html : `<p>Thanks for signing up...</p>` , }) }) await step . sleep ( ' wait-2-days ' , ' 2 days ' ) await step . run ( ' send-tips-email ' , async () => { await resend . emails . send ({ from : ' hello@yourapp.com ' , to : email , subject : ' Top 5 tips to get the most out of the app ' , html : `<p>Here are the tips...</p>` , }) }) await step . sleep ( ' wait