Developer tools

Everyday utilities for people who work with data and code.

JSON Formatter & Validator

Paste JSON to format, minify or validate it, with the exact line and column of any syntax error. Works offline and never uploads your data.

Unix Timestamp Converter

Convert a Unix timestamp to dates across time zones, or a date back to seconds and milliseconds. The assumed unit is always shown. Runs in your browser.

UUID Generator

Make 1 to 1000 UUIDs locally with the browser CSPRNG, including time-ordered v7 per RFC 9562. Copy the list or download a .txt. Nothing leaves your device.

JWT Decoder

Paste a JSON Web Token to inspect its header and payload, with exp, iat and nbf shown as real dates. UTF-8 safe, so Chinese claims stay readable.

Regex Tester & Regular Expression Validator

Test a regular expression on your own text with live match highlighting, capture groups, flag toggles and a replacement preview. Nothing uploaded.

Hash Generator & Checksum Calculator

Hash text or a file and get MD5, SHA-1, SHA-256, SHA-384 and SHA-512 at once in hex and Base64. Computed locally in your browser, nothing is uploaded.

Text Diff & Line Compare

Compare two texts line by line with unified and side-by-side views, added and removed counts, visible whitespace and a copyable diff. No uploads.

Markdown Viewer & Exporter

Preview Markdown live and export it as PNG, JPG, WebP, SVG, PDF or HTML at any size, with a page margin and a choice of themes like GitHub. No upload.

Base64 Encoder & Decoder

Encode or decode Base64 with Chinese, emoji and accented text handled correctly. Standard, URL-safe and MIME variants, files and data: URLs. No upload.

URL Encoder & Decoder

Percent-encode or decode text and links with encodeURIComponent, encodeURI or form (+) rules. Handles Chinese and emoji and explains bad sequences.

Markdown to HTML Converter

Convert Markdown to clean HTML with tables, task lists and heading ids. Choose how raw HTML is handled, wrap a full document, minify, copy or download.

HTML to Markdown Converter

Turn HTML or text copied from a web page into clean Markdown: headings, lists, links, images, tables and code blocks. Choose the style. Runs in your browser.