Text Tools
Remove Duplicate Lines
Strip repeated lines from multiline text while keeping first-seen order.
Open Remove Duplicate Lines
Explore all tools
Find the utility you need and open it instantly.
Developer Tools
JSON Formatter / Beautifier
Format and beautify JSON instantly with proper indentation.
Open JSON Formatter / Beautifier
Developer Tools
CSV to JSON Converter
Convert CSV data into structured JSON quickly.
Open CSV to JSON Converter
Developer Tools
JSON to CSV Converter
Convert JSON arrays of objects (or a single object) into CSV.
Open JSON to CSV Converter
Developer Tools
JSON to TypeScript Interface Generator
Generate TypeScript interfaces from JSON samples.
Open JSON to TypeScript Interface Generator
Text Tools
Text Diff Checker (Compare Text)
Compare two text blocks and highlight differences.
Open Text Diff Checker (Compare Text)
Text Tools
Remove Extra Spaces / Clean Text
Clean up extra spaces and normalize plain text.
Open Remove Extra Spaces / Clean Text
Developer Tools
Base64 Encoder
Encode plain text to Base64 instantly.
Open Base64 Encoder
Developer Tools
Base64 Decoder
Decode Base64 back to plain text.
Open Base64 Decoder
Developer Tools
URL Encoder
Encode text into URL-safe format instantly.
Open URL Encoder
Developer Tools
URL Decoder
Decode URL encoded strings back to plain text.
Open URL Decoder
Security Tools
Strong Password Generator
Generate strong random passwords with customizable character rules.
Open Strong Password Generator
Calculators
Percentage Calculator
Calculate percentages, increases, and decreases quickly.
Open Percentage Calculator
Frequently asked questions
Quick answers about using OnlineToolkit.
OnlineToolkit is a collection of free, fast browser utilities for text, developers, security, and everyday calculations. Open a tool, use it immediately, and leave when you are done.
No. The tools are available without signup. Your session stays in the browser for most utilities, so you can start working right away.
Most tools process input locally in your browser. We do not use your pasted text or files for training, and nothing is stored on our servers for typical client-side tools.
You need a network connection the first time you load a page. After that, many tools continue to work with cached assets until you refresh or clear site data.
Yes. OnlineToolkit is free to use. There are no paywalls for the utilities listed in the catalog.
Browse by category from the Categories page, open the full Tools directory, or use the search on the homepage and tools page to filter by name or description.
Use a current version of Chrome, Firefox, Safari, or Edge. Tools rely on modern JavaScript; very old browsers may not work correctly.
Yes. Copy the output from any tool and paste it into another—for example, format JSON, then convert or diff it in a follow-up step.
We ship improvements and new utilities regularly. Each tool page reflects the latest behavior when you load the site.
OnlineToolkit is built for interactive use in the browser. There is no public HTTP API; integrate by linking to the tools you need.
Check that your input matches the expected format—for example valid JSON for a formatter. Error messages usually point to the line or rule that failed.
Use your project’s issue tracker or contact channel if you are self-hosting. For the public site, check the repository or support link in the site footer if provided.