Free Developer Tools
Essential tools for developers — format, encode, convert and generate. All run in your browser, with nothing uploaded.
Last updated: June 2026
JSON Formatter & Validator
Beautify, minify and validate JSON with syntax highlighting, error line detection and key sorting.
Open toolBase64 Encoder / Decoder
Encode and decode Base64 for text or files, with URL-safe output and MIME line breaks.
Open toolColor Code Converter
Convert between HEX, RGB, HSL, HSV and CMYK, with a picker, contrast checker and CSS snippets.
Open toolMeta Tag Generator
Generate SEO, Open Graph and Twitter Card meta tags with live Google and social previews.
Open toolUTM Link Builder
Build campaign tracking URLs for Google Analytics, with one-click presets and a QR code.
Open toolPassword Generator
Create strong random passwords with crypto-grade entropy, custom character sets and bulk output.
Open toolRegex Tester
Test regular expressions live with match highlighting, capture groups, flags and common-pattern presets.
Open toolCSS Gradient Generator
Build linear, radial and conic gradients visually with a live preview and copy the CSS, Tailwind class or PNG.
Open toolFavicon Generator
Create a full favicon set from text, emoji or an image — every size plus a multi-size ICO and HTML snippet.
Open toolJSON to CSV Converter
Convert a JSON array to CSV or CSV back to JSON, with delimiter options and number parsing. Pure browser, no upload.
Open toolMarkdown to HTML Converter
Turn Markdown into clean HTML with a live preview — headings, tables, code blocks and task lists. Copy or download.
Open toolColor Palette Generator
Generate complementary, analogous and triadic palettes from one colour, with HEX/RGB/HSL and WCAG contrast checks.
Open toolTry these examples
Why use these developer tools?
Quick utilities you reach for every day — without the ad walls, sign-ups, or sending your data to someone else's server.
Zero dependencies
Every developer tool is built on pure browser APIs — no frameworks, no analytics on your input, no third-party libraries loaded to do the work.
Nothing is uploaded
JSON, secrets, passwords and URLs are processed entirely in your browser tab. We can't see them, store them, or transmit them anywhere.
No sign-up, no limits
Format a thousand JSON files, generate a hundred passwords — there's no account, no paywall, and no daily cap on any tool.
Fast and keyboard-friendly
Tools load instantly, work offline once cached, and are built to fit a developer's workflow with copy buttons and live updates.
A focused set of free online tools for developers.
Every developer keeps a handful of small utilities within arm's reach — something to pretty-print a tangled API response, a quick Base64 encoder and decoder, a way to turn a HEX color into RGB. CrispToolHub gathers the most useful of these into one fast, private place. There's nothing to install and no account to create, and crucially, every one of these developer tools online runs entirely in your browser — so the JSON you debug, the strings you encode, and the passwords you generate never touch a server.
Start with the JSON formatter and validator. Paste a minified or malformed blob and it beautifies the structure with syntax highlighting, or strips it back down with one click to minify. If the JSON is broken, it acts as a JSON validator online, telling you the parser's error and the line to look at. You can sort keys alphabetically, switch between two-space, four-space or tab indentation, and download the result as a .json file.
The Base64 encoder/decoder handles both text and files, with a URL-safe option and optional MIME line breaks; the color code converter turns any color into HEX, RGB, HSL, HSV and CMYK at once, with a built-in WCAG contrast checker for accessible text. Each format has its own copy button, and a ready-to-paste CSS snippet is generated for you.
For shipping, sharing and securing
When you're publishing a page, the meta tag generator builds a complete set of SEO, Open Graph and Twitter Card tags and previews exactly how your link will look in Google results and on social media. When you're promoting it, the UTM link builder assembles a clean campaign-tracking URL — with presets for Google Ads, email, Facebook, X, LinkedIn and Instagram — and generates a scannable QR code on the spot, all without a library.
And when you need credentials, the password generator produces strong, random passwords using the browser's cryptographically secure random source, with full control over length, character sets and how many to generate at once. Newer additions round out the set: a regex tester with live match highlighting and capture groups, a CSS gradient generator with linear, radial and conic modes, and a favicon generator that outputs every size plus a multi-size ICO. Like everything here, they're free, private, and built for the way developers actually work. Pick a tool above to get started.
How to get started
Three quick steps — no account, nothing uploaded to a server.
Choose a tool from below
Browse the tools on this page and pick the one that fits what you need.
Use it instantly — no account needed
Open it and start right away; everything runs free in your browser.
Download or copy your results
Save, copy or share your output in a click — nothing is uploaded to a server.
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FAQ
Frequently asked questions
What is a JSON formatter?
A JSON formatter (also called a JSON beautifier) takes minified or messy JSON and re-indents it into a clean, readable structure with consistent spacing, so you can read and debug API responses and config files. A good formatter also validates the JSON as it goes — flagging the exact line where a comma, bracket or quote is missing. Our free JSON Formatter & Validator does both right in your browser: paste your JSON, click Format, and get syntax-highlighted output, with a one-click Minify to strip whitespace back out when you need the smallest possible payload.
How do I encode text to Base64?
Base64 encoding converts text or binary data into a string of 64 safe ASCII characters (A–Z, a–z, 0–9, + and /), so it can travel through systems that only handle text — like embedding an image in CSS or putting binary data in a JSON field. To encode text, paste it into our Base64 tool in Encode mode and the Base64 string appears instantly; you can also drop a file to encode its bytes. Switch to Decode mode to reverse the process. Everything runs locally, so even sensitive strings never leave your device.
How do I convert HEX to RGB?
A HEX color like #3B82F6 packs three values — red, green and blue — into pairs of hexadecimal digits (3B = 59, 82 = 130, F6 = 246), giving rgb(59, 130, 246). You can convert by hand by reading each pair as a base-16 number, but our Color Code Converter does it live: type or pick any color and it instantly shows the equivalent HEX, RGB, HSL, HSV and CMYK values, each with a copy button, plus a CSS snippet you can paste straight into a stylesheet.
What are meta tags and why do they matter?
Meta tags are snippets of HTML in a page's <head> that tell search engines and social networks how to display it. The title and description shape your Google search snippet; Open Graph tags (og:title, og:image) control how a link looks when shared on Facebook or LinkedIn; and Twitter Card tags do the same for X. Getting them right improves click-through rates and how professional your links appear. Our Meta Tag Generator builds all of them from a simple form and shows live Google, Facebook and Twitter previews as you type.
What is a UTM parameter?
A UTM parameter is a tag added to a URL — like ?utm_source=newsletter&utm_medium=email&utm_campaign=spring_sale — that tells Google Analytics where a visitor came from. The five standard parameters are source, medium, campaign, term and content. By tagging your links, you can see exactly which email, ad or social post drove traffic and conversions. Our UTM Link Builder assembles a correctly formatted tracking URL from your inputs, offers one-click presets for common platforms, and even generates a QR code for the finished link.
How do I generate a secure password?
A secure password is long and random, drawn from a large mix of character types — uppercase, lowercase, numbers and symbols — so it can't be guessed or cracked by brute force. The key is true randomness: our Password Generator uses the browser's crypto.getRandomValues(), a cryptographically secure source, rather than the predictable Math.random(). Choose a length (16 or more is a good default), pick your character sets, and generate one or several at once. Each password is created locally and never transmitted or stored.
What is Base64 used for?
Base64 is used wherever binary data needs to be represented as plain text. Common cases include embedding small images directly in HTML or CSS as data URIs, encoding email attachments (the MIME standard), storing binary blobs in JSON or XML, and encoding basic-auth credentials in HTTP headers. It is an encoding, not encryption — it offers no security, just a safe text representation. Our tool supports URL-safe Base64 (which swaps + and / for - and _) for use in URLs and filenames.
How do I validate JSON online?
To validate JSON, paste it into a tool that parses it with a strict JSON engine and reports any syntax errors. Our JSON Formatter validates as you format: if the JSON is well-formed it pretty-prints it, and if it isn't, it shows the parser's error message and highlights the line where the problem is, so you can fix trailing commas, unquoted keys or mismatched brackets quickly. Because it runs in your browser, you can safely validate JSON that contains private or proprietary data.
What is the difference between HEX and RGB colors?
HEX and RGB describe the same thing — a color built from red, green and blue channels — in two notations. RGB is decimal, written as rgb(59, 130, 246) with each channel from 0 to 255. HEX is hexadecimal, written as #3B82F6, where each pair of digits is one channel. HEX is compact and common in CSS and design tools; RGB is easier to read and supports an alpha channel via rgba(). Our converter shows both at once (plus HSL, HSV and CMYK) so you can use whichever your tool expects.
How do I track links with UTM parameters?
Add UTM parameters to the end of any link you share, then read the results in Google Analytics under Acquisition reports. Decide on a consistent naming convention — lowercase, no spaces — for source (e.g. newsletter), medium (e.g. email) and campaign (e.g. spring_sale), and reuse it so your reports stay clean. Build the tagged URL with our UTM Link Builder, copy it, and use it in your email, ad or social post. When people click, Analytics attributes the visit to that exact source, medium and campaign.