Free online developer tools
Format JSON, compare text, convert data, calculate subnets and turn cURL commands into code — directly in your browser.
JSON formatter
POPULARFormat, validate and minify JSON.
Text diff
Compare two texts line by line.
CSV ↔ JSON
Convert between CSV and JSON.
cURL to code converter
Turn a cURL command into JavaScript, Python, PHP, Go or Node.js code.
Subnet / CIDR calculator
Get network, broadcast, mask and host range for any IPv4 address.
Cron expression generator
Build and validate cron schedules, then preview the next five run times.
Quick start
- 01
Choose the tool for your task.
- 02
Add a file or paste your text, then adjust the settings.
- 03
Check the result and download or copy it.
Frequently asked questions
Are these tools free?
Yes. These utilities are free to use without an account.
Do my files leave my device?
The utilities listed here process your files or text locally in your browser. Some engines download on first use, but your input is not uploaded.
What are the limits?
Practical limits depend on device memory and supported formats. Large files can take longer; you can use smaller batches.