60+ developer tools.
Zero round trips.
60+ dev tools that run entirely in your browser. Format JSON, decode JWTs, generate hashes, test regex, convert colors — instantly.
Pick a favourite
A handful of crowd-pleasers — start here, then explore the rest.
All 60+ tools
Organized into focused categories. Every tool runs locally in your browser.
JSON Tools
10 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.
Compare two JSON objects visually.
Sort JSON object keys alphabetically.
Escape or unescape JSON strings.
Validate JSON against a schema.
Encoding & Security
10 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.
Generate bcrypt password hashes.
Encrypt or decrypt text using AES.
Generate public/private RSA keys.
Generate QR codes from text or URLs.
API & Network
10 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.
Check website status codes instantly.
Test if a server port is open.
Inspect SSL certificate details of a domain.
Connect and test WebSocket endpoints.
Code Tools
12 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.
Beautify and format SQL queries.
Render Markdown into HTML preview.
Beautify and validate XML content.
Validate YAML syntax instantly.
Explain cron expressions in plain English.
Create test JWT tokens for development.
Utility Tools
12 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.
Convert length, weight, speed, and more.
Convert time between global timezones.
Calculate exact age from date of birth.
Calculate loan EMI payments instantly.
Calculate percentages and changes.
Convert binary, decimal, octal, and hex.
Image & Media Tools
6 tools
Reduce image size without losing quality.
Resize images to custom dimensions.
Convert images into Base64 strings.
Convert JPG/PNG images to WebP format.
Fetch thumbnails from video URLs.
Generate favicons for websites.
Developer Tools
6 tools
Parse and validate .env configuration files.
Generate gitignore files for frameworks.
Create SEO and OpenGraph meta tags.
Generate robots.txt for SEO.
Create XML sitemaps for websites.
Inspect dependencies from package.json.
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.
1Is FastDevTools really free?
Yes. No accounts, no paywalls, no premium tier. Every tool is browser-based and free to use forever.
2Do you store my data?
No. Tools run entirely in your browser. Your input never reaches a server we control.
3What 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.
4Can 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.
5Open source?
The site is intentionally simple — React + 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.
- 60+ tools across 7 categories
- Open URLs — share directly
- Works on mobile, tablet, desktop