Developer • July 2026 • 5 min read
10 Free Online Developer Tools You'll Use Every Week
Every developer keeps a mental list of small utilities: encode this, format that, what's this timestamp? Here is a complete free toolkit that runs in your browser — no accounts, no ads walls, and nothing sent to a server.
Encoding and data
- Base64 Encoder / Decoder — UTF-8 safe (emoji included) plus file-to-data-URL conversion for embedding images in CSS.
- URL Encoder / Decoder — component and full-URL modes, so query strings never break again.
- JSON Formatter — pretty-print, minify and validate API payloads.
- CSV ↔ JSON Converter — handles quoted fields and commas inside values, both directions.
Time and identity
- Unix Timestamp Converter — auto-detects seconds vs milliseconds and shows local, UTC and relative time, with the live current epoch.
- UUID Generator — instant v4 UUIDs for keys and fixtures.
Text and review
- Text Diff Checker — line-by-line comparison with added/removed highlighting, great for configs and content reviews.
- Text Cleaner — strip line breaks, collapse spaces, dedupe and sort lines.
Ship your site
- Color Converter — HEX, RGB and HSL with click-to-copy and light/dark contrast previews.
- Favicon Generator — 16 to 512px PNGs from an image, letter or emoji, with the HTML snippet included.
- Robots.txt Generator — correct crawler rules, AI-bot blocking and sitemap line in seconds.
- Meta Tag Checker — preview how titles and descriptions truncate in search results.
Try these free tools mentioned in this article: