JSON Formatter
Format, validate, and beautify JSON data with advanced error handling
developerjsonformatter
Runs 100% in your browser — no signup, nothing uploaded
Free Online Developer Tools, Calculators & Utilities — No Signup Required
A fast, privacy-first collection of 89 online tools — from developer utilities and converters to text processors. Everything runs in your browser, so your data never leaves your device.
- Free Tools
- 89
- 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
converterbase64encoder
JWT Decoder
Decode JSON Web Tokens to inspect header, payload, and claims with expiration check — 100% client-side
developerjwtdecoder
Regex Tester
Test and debug regular expressions with live matching
developerregextester
Color Palette Generator
Generate beautiful color palettes for your projects
designcolorpalette
Password Generator
Generate strong, secure passwords with custom options
developerpasswordgenerator
Markdown Editor
Preview and edit Markdown with live rendering
textmarkdowneditor
CSS Gradient Generator
Visual builder for linear, radial, and conic CSS gradients with live preview and Tailwind/SCSS export
designcssgradient
From the blog
Guides & deep-dives
Practical, spec-cited walkthroughs of the formats and tools you work with every day.
Featured20 min read
The Ultimate Developer Stack 2025: 50+ Tools to 10x Your Workflow
The 50+ developer tools worth using in 2025 — AI-native IDEs like Cursor, edge databases, and performance utilities — with what each one is best at.
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 free collection of 89+ online utilities for developers, designers, and anyone with a quick task. 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.
Why is everything free?
Toolk is funded by its maintainer as a community resource. Every tool is available to every visitor immediately, with no signup and no email address. The catalogue runs entirely in your browser, so there is nothing to install and nothing uploaded to a server.
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 aggregate pageview metrics we use Google Analytics 4 with no personally identifiable information collected and no cross-site tracking; your tool input data is never part of that telemetry.
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.
Free tools, no catch. What should we build next?
Every Toolk utility is free and runs in your browser. Have an idea for a tool that should exist? Suggest it — many tools here started as a request.