10 Free Developer Tools You Absolutely Need in 2026
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Every developer has a folder of bookmarks — online tools they return to daily. But most "free tools" are either bloated with ads, require signups, or sell your data. Here are 10 tools that don't do any of that. All open source. All free. All actually useful.
1. JWT Debugger
Decode and inspect JSON Web Tokens instantly. See the header, payload, expiration time, and signature — all color-coded and readable. No more squinting at Base64 in your terminal.
Use case: Debugging authentication flows. Checking token expiry. Verifying claims.
2. JSON Formatter & Validator
Paste minified JSON, get beautiful indented output. Invalid JSON? It tells you exactly where the error is. Supports huge payloads without crashing.
Use case: Reading API responses. Debugging config files. Pretty-printing compressed data.
3. Base64 Encoder / Decoder
One click to encode or decode Base64 strings. Handles Unicode properly (unlike half the tools on the first page of Google).
Use case: Decoding JWT payloads manually. Encoding binary data for JSON. Processing email attachments.
4. UUID Generator
Generate v4 UUIDs in bulk. Need 10 unique IDs for test data? One click. Need 100? One click. Copy them all at once.
Use case: Creating test fixtures. Generating unique keys. Database seeding.
5. Timestamp Converter
Unix timestamp → human readable. ISO date → Unix. Milliseconds or seconds — it auto-detects. Shows UTC, ISO, and local time simultaneously.
Use case: Debugging logs. Working with APIs. Converting timezones.
6. Regex Tester
Write a regex, paste test data, see results instantly. Match count, captured groups, full match list. No setup, no IDE required.
Use case: Validating email patterns. Extracting data from logs. Testing URL patterns.
7. SSL Certificate Checker
Enter any domain, instantly see certificate expiry, issuer, validity dates, and remaining days. Never let a cert expire again.
8. Broken Link Checker
Scan any website for 404 errors, broken redirects, and dead links. Free tier: 10 links. Pro ($5 USDC lifetime): 1000 links + API access.
9. Website Screenshot Generator
Generate beautiful screenshots of any URL. Plus a built-in JSON-to-table renderer for quick data visualization.
10. AI Prompt Library
50+ curated AI prompts for developers. Code review, API docs, SQL optimization, refactoring — all tested and optimized. Free tier: 4 prompts. Pro ($5 USDC): all 50+.
All 10 tools are free and open source. No ads. No tracking. No account required.
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