10 Free Online Developer Tools You Should Bookmark Today
Save hours of development time with these free browser-based developer tools — no installation, no account, works anywhere.
Why Use Browser-Based Developer Tools?
Every developer has a toolkit — but installing and maintaining desktop software takes time. Browser-based tools are instant: open a URL, paste your data, get your result. No installation, no updates, no licence fees. Here are 10 tools worth bookmarking.
1. JSON Formatter & Validator
The most-used tool in any developer's day. Our JSON Formatter instantly beautifies compressed JSON from APIs, config files, or logs. The companion JSON Validator tells you exactly which line has a syntax error — a lifesaver when chasing a missing comma in a 500-line config.
2. Base64 Encoder / Decoder
Base64 encoding is everywhere: image embedding in CSS, JWT tokens, email attachments, and API authentication headers. Our Base64 Encoder/Decoder handles the conversion instantly, including URL-safe Base64 (replacing + with - and / with _).
3. JWT Decoder
JWTs (JSON Web Tokens) are used in almost every modern authentication system. When you need to inspect the claims inside a token — without verifying the signature — our JWT Decoder splits the header and payload and displays them as readable JSON. Runs entirely in your browser, so your token never leaves your machine.
4. UUID Generator
Need a unique ID for a database record, file name, or test fixture? Our UUID v4 Generator produces cryptographically random UUIDs instantly. We also offer NanoID and ULID generators for modern use cases.
5. SHA-256 Hash Generator
Hash a password, verify a file checksum, or test your hashing implementation with our SHA-256 Hash Generator. Uses the browser's native Web Crypto API — no third-party library, same algorithm your server uses. We also support SHA-1, SHA-512, and MD5.
6. Regex Tester
Writing a regular expression without testing it is asking for trouble. Our Regex Tester shows matches in real time as you type — paste your pattern, paste your test string, and see exactly what matches. Supports JavaScript regex syntax including flags (g, i, m).
7. URL Encoder / Decoder
Special characters in URLs break requests. Our URL Encoder converts spaces, ampersands, and other characters to percent-encoded form. The decoder does the reverse — useful when debugging redirect chains or parsing query strings from logs.
8. CSV to JSON Converter
Received data in a spreadsheet but need it in JSON for your API? Our CSV to JSON Converter parses the headers automatically and outputs a clean JSON array. The reverse — JSON to CSV — exports any flat JSON array to spreadsheet format.
9. YAML Formatter & Validator
Kubernetes configs, GitHub Actions, and Docker Compose files all use YAML — and YAML's whitespace sensitivity makes it easy to break. Our YAML Formatter normalises indentation, and the YAML Validator catches tab characters and other common mistakes before they reach your CI pipeline.
10. Cron Expression Generator
Cron syntax is cryptic. Our Cron Expression Generator gives you common schedule patterns as a reference — from "every 15 minutes" to "first Monday of the month" — so you don't have to memorise the field order.
Browse All Developer Tools
These 10 are just the start. ToolHive has 130+ free developer tools covering encoders, hash generators, CSS tools, code formatters, validators, and more. All free, all browser-based, no signup required.