CapyToolkit is a free collection of browser tools, positioned as "tools that run in your browser," emphasizing that all calculations are performed locally on the client side, with no files or input content uploaded, no installation, no account, and no payment required.
Purpose For users who need hardware testing, development assistance, audio analysis, engineering calculations, security and privacy processing, web design, network reference, and everyday personal tasks, it provides a variety of practical tools accessible within a single browser tab.
Main capabilities According to the official introduction, the tools are divided into the following categories (the number already launched is shown in parentheses):
- Hardware and display diagnostics (6): real tests for monitors, mice, cameras, MIDI devices, etc.
- Developer parsing and encoding (10): format, encode, decode, inspect, without opening the network panel.
- Text analysis and conversion (3): case conversion, readability scoring, diff comparison.
- Audio and acoustic testing (3): microphone check, speaker sweep, decibel calculation, without plugins.
- Math and engineering calculations (5): Ohm's law, resistance, unit conversion.
- Security and privacy tools (9): hashing, redaction, checking sensitive data, without uploading.
- Web design CSS tools (3): contrast checking, gradients, color conversion.
- Network and web reference (6): parse URLs, request headers, subnets, without leaving the tab.
- Personal tools (6): passport photos, PDFs, and everyday calculators, completed on this device.
Latest added and already launched tools:
- PDF to Markdown converter (personal tool): convert PDFs to Markdown on this device; scanned pages can use a local AI model, without uploading any content.
- Receipt item splitter (personal tool): assign receipt lines to different people on this device and split taxes and tips, without uploading any content.
- Phone-scanned document correction to PDF (personal tool): correct trapezoidal document photos taken with a phone into clean multi-page PDFs, completed on this device, without uploading any content.
- Local PDF toolkit (personal tool): merge, split, reorder, rotate, and compress PDFs on this device, without uploading any content.
- Compress image to size limit (personal tool): compress an image on this device to the file size limit for email, forms, or apps, without uploading any content.
- Passport and visa photo cropper (personal tool): crop passport or visa photos on this device to official millimeter dimensions and adjust eye-line position, without uploading any content.
- OfflineAnd private AI text detector (text analysis and transformation): completely offline, privately assess how AI-generated a text is in the browser, no registration, no paywall.
- JSON formatter, validator and tree viewer (developer parsing and encoding): pretty print, minify, and browse JSON in a collapsible tree structure with syntax highlighting.
- Regex tester and match debugger (developer parsing and encoding): real-time match highlighting, capture group display, and step-by-step debugging for any pattern.
- WCAG contrast checker (web design CSS tools): supports hex, RGB and HSL input, performs AA and AAA contrast ratio tests.
How to use Open the website and use it, no installation or registration required. Some tools support installation as an app (374 users have already installed it); after installation, all tools can be accessed with one tap from the home screen and are cached locally, so they remain usable in environments with no signal, such as on a plane or on restricted networks. The website uses anonymous, cookie-free analytics (before you click “Accept”), and tool input never leaves the browser.
Use cases
- Hardware tests that require local execution to complete (for example, detecting dead pixels on a monitor).
- When handling sensitive data (such as JWT tokens or JSON responses containing personally identifiable information), avoid pasting it into online forms.
- Lightweight tools that need to be used instantly, with no cold start and no API round trip.
- Scenarios that are free, with no account, no rate limits, and no “upgrade to Pro” pop-ups.
- Situations that require offline use, such as on a plane, in a secure lab, or in an environment without internet access.
Limitations The materials do not provide a complete list of specific tools, detailed feature descriptions for each tool, pricing, platform support scope, or effectiveness or performance data. Some content (such as the roadmap or blog post titles) is mentioned but not elaborated on, so its specific content cannot be confirmed.
