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Yunknow Toolbox

Online Tools

A growing set of free developer and everyday tools — formatters, encoders, generators and converters. Everything runs locally in your browser; nothing is uploaded. The examples on each tool page are real output rather than something written from memory: the MD5 of `hello` is 5d41402abc4b2a76b9719d911017c592, and 255 comes back from our base converter as hex `ff` and binary `11111111`. Every one of those is checkable with your own tools.

Jump straight to any of the 30

Developer

JSON Formatter

Beautify, minify and validate JSON in one click, with automatic error detection.

JSON ⇄ CSV ⇄ Excel Converter

Convert tabular data between JSON, CSV and Excel (.xlsx) — free, fast and entirely in your browser.

Unix Timestamp Converter

Convert between Unix timestamps and human-readable date-time in real time.

UUID Generator

Batch-generate UUID v4 with one-click copy — great for testing and database keys.

Regex Tester

Test regular expressions live, highlight matches, with flags and capture groups.

JSON ⇄ YAML Converter

Convert data between JSON and YAML in your browser — free, fast and no upload.

Markdown ⇄ HTML Converter

Convert Markdown to HTML or HTML back to Markdown in your browser, with a live preview and no upload.

Cron Expression Generator

Read and build cron schedule expressions, with a plain-English explanation and a "next runs" preview — all in your browser.

Number Base Converter

Convert between binary, octal, decimal and hex live — and turn text into binary or hex.

XML Formatter

Beautify, minify and validate XML in one click, with automatic error detection.

Roman Numeral Converter

Convert between numbers and Roman numerals live (1–3999) — edit either side and the other updates.

Meta Tag Generator

Fill a few fields to instantly generate SEO title/description, Open Graph and Twitter Card tags — with a search preview.

SQL Formatter

Turn one-line SQL into clean, indented queries — supports MySQL, PostgreSQL, SQLite and more, with optional keyword casing.

Text

Word Counter

Instantly count words, characters, sentences, paragraphs and reading time.

Case Converter

Switch between UPPERCASE, lowercase, Title Case, camelCase, snake_case and more in one click.

Chinese Converter (Traditional ⇄ Simplified)

Convert between Traditional (Taiwan) and Simplified Chinese — including vocabulary — in your browser. Free, no upload.

Text Cleaner

Remove line breaks, delete duplicate lines, strip empty lines, collapse spaces and sort — all in your browser.

Text Diff / Compare

Paste two texts and instantly see additions, deletions and differences — line or word level.

Morse Code Translator

Translate between text and Morse code live — letters, numbers, punctuation, and playable beeps.