Free online tools that just work.
Fast, simple utilities for converting, calculating, formatting, generating, and creating — directly in your browser. No signup. No uploads. No tracking.
Private by design
Files and text are processed in your browser and never uploaded. Turn off your network and every tool still works.
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No signup, no paywalls, no waiting. Tools load instantly from a global edge network.
Simple
Each tool does one thing well. No clutter, no dark patterns, no modal traps. You land, you use it, you leave.
Popular tools
The most-used tools on Uttir. Click any to open it instantly.
JSON Formatter
Format, beautify, and validate JSON with adjustable indentation — instantly in your browser.
Developer Tools
UUID Generator
Generate cryptographically random UUID v4 identifiers, one or a thousand at a time.
Developer Tools
Base64 Encoder
Encode any text — including emoji and non-Latin scripts — into standard Base64.
Developer Tools
JWT Decoder
Decode a JWT’s header and payload and check its expiration — without sending it anywhere.
Developer Tools
JWT Sign (HS256 / RS256)
Sign a JSON Web Token with HS256 (HMAC shared secret) or RS256 (RSA private key). Output is a standard compact JWT (header.payload.signature).
Security Tools
HMAC Generator
Compute a Hash-based Message Authentication Code (HMAC) for any message and shared secret. Supports SHA-256, SHA-512, SHA-1, and MD5. All computation runs in your browser.
Security Tools
Regex Tester
Test and debug regular expressions with live matches, capture groups, and highlighted results.
Developer Tools
Word Counter
Count words, characters, sentences, and paragraphs in your text instantly.
Text Tools
Percentage Calculator
Three percentage tools in one: percent of a value, ratio as a percent, and percent change.
Calculators
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From the blog
How to Calculate Permutations and Combinations (with Worked Examples)
A practical guide to counting: the difference between permutations (order matters) and combinations (order does not), the formula for each, the common real-world cases, and how to run the calculation in your browser without pulling out a calculator or a textbook.
Aug 31, 2026 · 6 min read
How to Split Startup Equity Fairly (and Why 50/50 Is Usually Wrong)
A practical guide to splitting equity between co-founders: the four factors that actually drive a fair split, the standard 4-year vesting with 1-year cliff, why equal splits are usually wrong, and how to use a simple calculator to test your split before it is too late to change.
Aug 31, 2026 · 5 min read
How to Explore a JSON File Visually (and Stop Scrolling)
JSON files get long fast. A 5,000-line config file or a 50 KB API response is unreadable as raw text. This guide covers the right way to navigate a JSON document: tree views, search, path navigation, and the moves that turn a wall of text into something you can actually work with.
Aug 31, 2026 · 5 min read
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