CapyToolkit is a growing collection of free, privacy-first browser tools, and it exists because a solo developer got tired of web utilities that ask for an account, an upload, or an email address before doing ten seconds of work. Every one of its 50+ tools computes in the browser, so nothing you type, paste, record, or open reaches a server.
The catalog is deliberately practical and covers nine categories: hardware, developer, security, audio, math, text, design, network, and personal. The hardware testers check the things people actually suspect are broken. A gamepad stick drift tester shows how far a thumbstick has wandered from center and how quickly it returns. A mouse polling rate meter reads the true input rate instead of trusting a label. There are dead pixel checks for a monitor, webcam lighting tests, a speaker sweep for frequency response, and microphone noise floor and latency measurements.
The developer and security tools work on things you paste or open locally. A JWT decoder reads a token's header and claims. JSON formatting, validation, and diffing keep a payload readable. A SQL runner works over local files. An EXIF scrubber strips photo metadata, and offline OCR redaction blurs sensitive text in an image on your machine.
The personal tools cover the everyday jobs. A passport photo cropper trims and sizes a photo to the printed requirements. A PDF toolkit merges, splits, and converts documents, including a PDF to Markdown converter. A phone-scan deskew straightens a photographed page. An image shrinker gets a file under a size limit, and a receipt splitter splits a long receipt photo into single receipts.
How it runs matters as much as what it does. CapyToolkit works as a website, installs as a progressive web app, and is available in the Microsoft Store for Windows. Once installed it works offline. It is always free, with no account, no upload, and no paywall. Every tool page includes worked examples and reference documentation, and there is a blog with deeper guides plus a public changelog and roadmap.
Indie makers, early adopters, PC builders, streamers, and everyday users use CapyToolkit for a fast hardware check, a PDF fix, or a passport photo. New tools ship on a regular schedule, and feedback on what to build next is welcome.
A few honest limits. The interface is English only, some tools ask for camera, microphone, or MIDI permission, there are no native mobile apps because the PWA installs on mobile instead, there is no public API, and the source code is not open. The catalog launched in 2026. For single-purpose alternatives, CyberChef and DevUtils cover parts of the security and developer range, and an Eizo Monitor Test covers parts of the display check.
