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 85 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 ads
There is nothing to sign up for and no "pro" tier hiding the useful half. There are also no ads — no banners, no interstitials, no ad network watching where you go next. 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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ssh-keygen -t ed25519
Why ssh-keygen -t ed25519 is the right default, how Ed25519, ECDSA and RSA compare, what quantum computing really changes, and using one key for Git and SFTP.
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How Random Is a UUID? Entropy, v4, and v7
A v4 UUID carries 122 bits of randomness; a v7 carries 74. How each is built, where each is used, and why randomness and entropy are not the same thing.
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How to Choose a Web Framework (Without Reading 50 Listicles)
A decision framework for picking a web framework: the four questions that actually narrow the field, and why team familiarity beats benchmarks.