Andergrove Software
Free online tools for developers and everyday tasks.
Fast, private browser tools that need no account — validate JSON, decode JWTs, generate passwords and QR codes, convert units and more. Everything runs locally in your browser, so nothing you paste ever leaves your device.
Popular tools
View all 77 tools →-
JSON Validator
Validate and pretty-print JSON with clear error messages that point at the problem.
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Base64 Encoder / Decoder
Encode and decode Base64 text and files, with Unicode- and URL-safe options.
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JWT Decoder & Encoder
Decode a JSON Web Token's header and payload, check expiry, and verify the signature.
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Password Generator
Create strong, random passwords with adjustable rules and a live strength meter.
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QR Code Generator
Turn any link or text into a sharp QR code and download it as PNG or SVG.
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Regex Tester
Test regular expressions with live match highlighting and capture groups.
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Diff Checker
Compare two versions of text and see exactly what was added and removed.
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Word & Character Counter
Count words, characters, sentences and reading time live as you type.
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Image Compressor & Resizer
Shrink and resize JPG, PNG and WebP images right in your browser — nothing is uploaded.
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Unix Timestamp Converter
Convert Unix timestamps to dates and back, in both local time and UTC.
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Unit Converter
Convert length, weight, temperature and volume between metric and imperial.
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Percentage Calculator
Work out percent of a number, one number as a percent of another, and percentage change.
Private by design — everything runs in your browser
Nothing you type is uploaded
Every tool here does its work locally, in your browser — the JSON you validate, the passwords you generate, the files you encrypt or compress never touch a server. That's not a policy promise you have to trust; it's how the tools are built, and you can verify it in your browser's network tab. It also means most tools keep working with the connection off.
No accounts, no paywalls, no nags
There is nothing to sign up for and no "pro" tier hiding the useful half. The site is supported by ads, which pays for a simple deal: the tools stay fast, free and complete, and you get an answer in seconds instead of a funnel. Bookmark the one you need — it'll behave the same next month.
A guide behind every tool
Each tool ships with a companion guide that goes deeper than the widget — how password cracking actually works, what your loan's amortization schedule really says, how to read hex fluently. The writing section collects the longer explainers.
Browse by category
Latest writing
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Cron Syntax Explained
The five cron fields, the schedules everyone actually needs — every 5 minutes, daily at midnight, weekdays at 9 — and the day-of-month/day-of-week trap that surprises everyone.
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How to Format SQL
Keyword casing, leading vs. trailing commas, indentation that shows query structure, and JOIN/CTE layout — the handful of SQL formatting rules that make queries reviewable.
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How to Unscramble Words
Anagram-solving techniques that actually work: alphagrams, prefix/suffix chunking, why RETINAS has eight anagrams, and the letter math behind Scrabble, Wordle and jumbles.