JSON Formatter
Format, validate, and beautify JSON data with advanced error handling
Freedeveloperjsonformatter
Runs in your browser — no signup, tool inputs are not uploaded
90Free Online Developer Tools, Calculators & Utilities
A fast, privacy-first collection of 90 online tools — from developer utilities and converters to text processors. Tool inputs are processed in your browser, so the data you paste or upload is not sent to Toolk.
- Free Today
- 90
- Client-Side
- 100%
- Uploads
- 0
Start here
Featured tools
A handful of the most-used utilities across the catalogue. Each opens instantly — no setup, no account.
Base64 Encoder
Convert plain text to Base64 format instantly with Unicode support
Freeconverterbase64encoder
JWT Decoder
Decode JSON Web Tokens to inspect header, payload, and claims with expiration check — 100% client-side
Freedeveloperjwtdecoder
Regex Tester
Test and debug regular expressions with live matching
Freedeveloperregextester
Color Palette Generator
Generate beautiful color palettes for your projects
Freedesigncolorpalette
Password Generator
Generate strong, secure passwords with custom options
Freedeveloperpasswordgenerator
Markdown Editor
Preview and edit Markdown with live rendering
Freetextmarkdowneditor
CSS Gradient Generator
Visual builder for linear, radial, and conic CSS gradients with live preview and Tailwind/SCSS export
Freedesigncssgradient
Browse by task
Find the right tool category
Browse focused category pages that group related utilities by the job they perform and connect them to relevant standards, examples, and practical guides.
31 tools
Developer Tools
These developer tools handle the small, repeatable jobs that interrupt real engineering work: formatting payloads, validating syntax, decoding tokens, generating identifiers, and inspecting web metadata. Each utility opens directly in the browser and produces usable output without an account. Tool inputs are processed on your device, so private code and payloads are not uploaded to Toolk.
Browse developer29 tools
Converters
Toolk converters transform structured data, measurements, dates, encodings, and files without sending the input to a conversion server. Use directional pages for precise tasks such as CSV to JSON, JSON to CSV, PX to REM, or REM to PX. Each page documents its parsing rules, rounding behavior, supported formats, and the edge cases most likely to change the result.
Browse converters13 tools
Text Tools
These text tools remove mechanical work from writing, editing, documentation, and data cleanup. Count words, normalize case, sort or deduplicate lines, run find-and-replace, build Markdown tables, or convert Markdown to HTML. Processing happens in the browser, which keeps unpublished drafts, customer lists, and internal notes out of a remote text-processing service.
Browse text17 tools
Design Tools
Toolk design utilities turn visual decisions into production-ready values. Build color palettes, verify WCAG contrast, mix or convert colors, generate CSS layouts and effects, create favicon packages, or compress images. The working preview appears beside the controls, and every generator exposes the CSS or file output needed to move the result into a real project.
Browse designFrom the blog
Guides & deep-dives
Practical, spec-cited walkthroughs of the formats and tools you work with every day.
Featured14 min read
Browser-Based Developer Tools for 20 Everyday Tasks
A practical map of 20 browser-based developer tools for formatting, conversion, debugging, security, CSS, and web metadata, with limits and source standards.
Web Development 11 min read
Unix Timestamps and Epoch Time: The Complete Developer Guide
A Unix timestamp counts seconds since 1970-01-01T00:00:00 UTC, ignoring leap seconds. Learn seconds vs milliseconds, the Year 2038 problem, and conversion.
Design 9 min read
px vs em vs rem in CSS: Which Unit to Use and When
px is an absolute pixel, em is relative to the element's own font-size, rem is relative to the root. Default to rem for accessibility — here is why and when.
SEO 11 min read
Open Graph & Meta Tags: The Complete Guide to Social Link Previews
The SEO title and meta description shape your SERP result; Open Graph and Twitter Card tags control how your link looks on Facebook, LinkedIn, X, and Slack.
About Toolk
What is toolk.site?
What does Toolk do?
Toolk is a collection of 90 online utilities for developers, designers, and anyone with a quick task. 90 current tools are marked free. The catalogue spans JSON formatting and validation, Base64 and other encoders, regex testing, text processing, color tooling, image optimisation, accessibility auditing, and dozens of everyday calculators for finance, health, and dates. Every tool ships with the same constraint: do exactly one job, do it fast, and export clean output you can paste into a PR, a ticket, or production code.
How are current tools priced?
Access and pricing are properties of each tool, not a permanent platform promise. All 90tools in today's catalogue are marked free and open without signup. An existing free tool will not be retroactively placed behind a paywall.
How does the privacy model work?
Every tool runs 100% client-side in your own browser using JavaScript. Your tool input — JSON payloads, API keys, passwords, files, image bytes — never leaves your device and is never transmitted to any server we control. For page-use measurement, Google Analytics 4 receives page, session, device, browser, and approximate-location information. Tool input is never included in that telemetry. Read the privacy policy for the complete disclosure.
Who runs Toolk?
Toolk is built and maintained by M H Tawfik under Soft Web Grove. The full mission statement, principles, and contact details are on the About page.
Useful tools, ready when you are
All 90 current catalogue tools are marked free and process tool input in your browser. Have a useful idea? Send a suggestion.