30 developer tools.
Zero round trips.
30 dev tools that run entirely in your browser. Format JSON, decode JWTs, generate hashes, test regex, convert colors — instantly, in your browser.
Pick a favourite
A handful of crowd-pleasers — start here, then explore the rest.
All 30 tools
Organized into focused categories. Every tool runs locally in your browser.
JSON Tools
6 tools
Pretty-print and indent JSON instantly.
Strip whitespace to compress JSON.
Check if JSON is syntactically valid.
Convert a JSON array of objects into CSV.
Translate JSON into well-formed XML.
Convert JSON into readable YAML.
Encoding & Security
6 tools
Encode or decode Base64 text.
Percent-encode or decode URLs.
Decode JWT header and payload (no signature verification).
Generate MD5, SHA-1, SHA-256, SHA-512 hashes.
Create strong random passwords.
Compute HMAC with SHA-256/384/512.
API & Network
6 tools
Send HTTP requests from your browser.
Inspect response headers of any URL.
Look up your public IP and basic info.
Parse a UA string into browser/OS/device.
Resolve A, AAAA, MX, TXT records via DoH.
Convert a cURL command to fetch() code.
Code Tools
6 tools
Format and indent HTML markup.
Remove whitespace and comments from CSS.
Compact JavaScript by removing whitespace.
Compare two text blobs line-by-line.
Test regular expressions against sample text.
Convert text between case styles.
Utility Tools
6 tools
Convert between Unix timestamps and dates.
Generate v4 UUIDs.
Convert between HEX, RGB, and HSL.
Generate placeholder text by paragraphs/words.
Pick random integers in any range.
Count words, characters, sentences, lines.
Built for speed and privacy
Every tool is built with the same principles: zero servers, zero accounts, instant results.
Runs in your browser
No data ever leaves your machine. Tokens, payloads, snippets — all processed locally with vanilla JavaScript.
Instant feedback
Tools respond in under 100ms. No spinners, no third-party calls, no waiting.
No accounts, no ads
No sign-up, no upsell, no tracking pixels. Bookmark a tool and use it forever.
Open standards
WebCrypto for hashes/HMAC, Cloudflare DoH for DNS, ipify for IP — all public, free APIs.
Mobile friendly
Responsive layouts and touch-friendly controls — debug from your phone, your iPad, anywhere.
Lightweight
Under 30 KB of JavaScript (gzipped) for the entire suite. Loads on dial-up.
Frequently asked
Everything you might want to know — in 30 seconds.
1 Is FastDevTools really free?
Yes. No accounts, no paywalls, no premium tier. Every tool is browser-based and free to use forever.
2 Do you store my data?
No. Tools run entirely in your browser. Your input never reaches a server we control.
3 What about IP/DNS lookup tools?
Those use public APIs (ipify.org, Cloudflare 1.1.1.1) called directly from your browser — we never see the request.
4 Can I use these tools offline?
Mostly yes — once a tool page is loaded it works offline. Network-dependent tools (DNS lookup, IP finder) need a connection.
5 Open source?
The site is intentionally simple — Laravel + Tailwind + vanilla JS. Reach out via the contact page if you want the source.
Bookmark it.
You'll be back.
FastDevTools is the simplest way to format, decode, generate, and test — without leaving your browser.
- 30 tools across 5 categories
- Open URLs — share directly
- Works on mobile, tablet, desktop