Private by design
Formatting, decoding, hashing and generating all happen locally on your device. Tokens and payloads never travel anywhere.
Free developer tools, by Zase
Developer tools that run entirely in your browser
Format JSON, decode JWTs, test regular expressions, generate hashes, QR codes and more. Free, private, and with no sign up: everything you paste stays on your device.
- 100% Free
- Runs Offline
- No Tracking
- Open Source
JSON Formatter
Format, validate, minify, sort, tree view and convert JSON.
Number Base Converter
Convert integers between binary, octal, decimal, hex and more.
SQL Formatter
Format SQL with clause breaks and keyword casing.
JSON to Types
Turn a JSON sample into TypeScript, Go or Python types.
CSS Formatter & Minifier
Format CSS with clean indentation, or minify it for production.
User Agent Parser
Paste a user agent string and see the browser, OS and device inside it.
YAML Formatter & Converter
Format and validate YAML, or convert between YAML and JSON.
XML Formatter & Validator
Format and validate XML, or minify it for production.
JSONPath Tester
Query a JSON document with a JSONPath expression and see every match.
UUID & ID Generator
Generate UUID v4/v7, ULID and Nano ID values. Validate any ID.
Password Generator
Strong crypto-random passwords, passphrases and PINs.
QR Code Generator
Turn text or a link into a QR code. Fully offline.
Favicon Generator
Make a full favicon set (PNG sizes plus favicon.ico) from an image or text.
Text Utilities
Counts, sort lines, dedupe, trim whitespace.
Diff Checker
Compare two texts line by line, with word-level highlights.
Lorem Ipsum
Generate placeholder text in Latin or custom words.
Markdown Preview
Write Markdown, see the rendered result, copy the HTML.
Meta Tag Generator
SEO, Open Graph and Twitter meta tags, generated live.
Slug Generator
Turn titles and headings into clean, URL friendly slugs.
HTTP Status Codes
Searchable reference for all HTTP status codes.
Cron Parser
Parse cron expressions into human-readable form. Builder included.
chmod Calculator
Build Unix permissions: checkboxes, octal and symbolic views.
IP Subnet Calculator
Network, broadcast, mask and host ranges for any IPv4 subnet.
Why developers pick Zase
Most online tools send what you paste to a server. Zase was built to never do that, on this site and in the extension.
Works fully offline
The Chrome extension runs with no connection at all. On the web, every tool works right in the tab, with nothing to install.
Instant, no waiting
No uploads, no queues, no server round trips. Paste, click, done: results appear as fast as your device can compute them.
Free, no account
Every tool is free, with no sign up, no trial timer and no locked features. Open a page and start working.
Chrome extension
Every tool, one shortcut away
Developer Toolkit by Zase packs the same tools into a free Chrome extension: fully offline, in a standalone window or docked in the side panel, with favorites, recents and a right-click menu that sends selected text straight into a tool.
- Fully offline after install: planes, trains and bad wifi are fine
- Side panel view keeps a tool next to the page you are reading
- Favorites and recents put your daily tools one click away
- Only four permissions, each tied to a visible feature
Add to Chrome: it is free
Frequently asked questions
Is Zase really free?
Yes. Every tool on this website and in the Chrome extension is free, with no locked features, no trial period and no premium tier. There is nothing to unlock because there is nothing to pay for.
Does my data leave my device?
No. Every tool runs locally in your browser tab or in the extension on your device. Nothing you type, paste or generate is uploaded, logged or sent to a server, because there is no server involved in the work at all.
Do I need an account?
No. There are no accounts, no sign up forms and no sign in. Open a tool page and start working, or install the extension and it is ready immediately.
What is the difference between the website and the extension?
The tools themselves are the same. The website needs nothing installed and suits quick one-off jobs. The extension works fully offline, opens in a window or the side panel, and adds favorites, recents, a quick search and a right-click menu for selected text.
Which browsers are supported?
The website works in any modern browser, including Chrome, Edge, Firefox and Safari. The extension is built for Chrome and also works in Chromium based browsers such as Edge and Brave.
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Thirty-six tools, zero uploads. Pick one above, or keep them all in Chrome.