Zero to Kilo
Free tools that run in your browser
ZEKILO is a set of web tools for everyday files and code. The files you open and the text you paste are processed on your own device, not uploaded to a server.
ZEKILO Studio
File tools
Compress and convert images, merge and split PDFs, and convert or trim video and audio without uploading your files.
All file toolsZEKILO Dev
Developer tools
Format JSON, encode Base64 and URLs, decode JWTs, convert Unix time and test regular expressions. What you paste stays in your browser.
- JSON Formatter & Validator
- Base64 Encode & Decode
- URL Encode & Decode
- JWT Decoder
- Unix Timestamp Converter
- Regex Tester
How the tools work
Open a file or paste text
Pick a file from your device or paste text into the tool. Nothing is sent when you do.
Your browser does the work
The page loads the tool once, then processing runs on your device with JavaScript and WebAssembly.
Save or copy the result
Download the result or copy it. There is no account, and your files are not stored on a server.
Guides
Short explanations written alongside the tools.
- Studio128 vs 192 vs 320 kbps MP3: quality & size per song
- StudioHow to convert iPhone HEIC photos to JPG: 3 ways
- StudioMOV vs MP4: what's the difference?
- DevJSON to Excel: CSV with UTF-8 BOM, Commas and Quotes
- DevDecoding a JWT vs Verifying It: Reading exp and iat
- DevWhy Non-ASCII URLs Turn Into %EC%A0%9C: Percent-Encoding
Calculators in Korean and Japanese
The ZEKILO calculators (take-home pay, VAT and consumption tax, loans, exchange rates, unit and date conversion) follow Korean and Japanese rules, so they are available in those two languages.