26 Free Online Developer Tools — No Signup, No Install (2026)
Most "free developer tools" lists link to GitHub repos you need Node.js to run locally, or SaaS products with a login wall. Everything below runs in a browser tab, handles your data client-side or deletes it from the server within 30 minutes, and requires no account of any kind. All 26 tools are at at-use.com . Grouped by what you are actually trying to do. Encoding & Decoding Base64 Encoder/Decoder — Encode text or binary to Base64, or decode it back. UTF-8 text and binary file payloads both work. Runs in your browser — nothing sent to a server. URL Encoder/Decoder — Percent-encode strings for safe URL inclusion, or decode percent-encoded URLs back to readable text. Handles both application/x-www-form-urlencoded and RFC 3986 encoding modes. HTML Entity Encoder/Decoder — Convert special characters to named HTML entities ( < → < , & → & ) or decode entities back to characters. Useful when building template strings or sanitizing output for display. Binary Translator — Text to binary, binary to text, or translate between binary, decimal, hex, and octal. Useful for low-level debugging and learning number representations. Number Base Converter — Convert integers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). All four outputs shown simultaneously. JWT Decoder — Paste a JWT token to decode and inspect the header and payload. Runs entirely in the browser — your token never leaves your machine. JSON & Text JSON Formatter & Validator — Format, validate, and minify JSON in one click. Toggle between pretty-print and compact output. Syntax errors include the exact line and column number. Uses browser-native JSON.parse() — no data sent anywhere. Text Diff — Side-by-side text comparison with no character limit (diffchecker.com caps at 25,000 characters on the free tier). JSON-aware mode auto-formats both inputs before diffing so whitespace differences do not pollute the output. Case Converter — 12 text case