Developer Tools
Format, convert, encode and generate developer-focused utilities.
Explore the Developer Tools collection
13 browser-based tools
Your all-in-one toolbox for everyday online tasks.
Convert, generate, edit, optimize, and analyze in seconds. OnlineToolkit helps you get work done with no installation and no friction.
Find a tool instantly
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13 tools available across 4 categories.
Popular categories
Browse tools grouped by what you need to solve.
Featured tools
Browse tools from your current catalog data.
Text Tools
Remove Duplicate Lines
Strip repeated lines from multiline text while keeping first-seen order.
Launch Remove Duplicate Lines
Developer Tools
JSON Formatter / Beautifier
Format and beautify JSON instantly with proper indentation.
Launch JSON Formatter / Beautifier
Developer Tools
CSV to JSON Converter
Convert CSV data into structured JSON quickly.
Launch CSV to JSON Converter
Developer Tools
JSON to CSV Converter
Convert JSON arrays of objects (or a single object) into CSV.
Launch JSON to CSV Converter
Developer Tools
JSON to TypeScript Interface Generator
Generate TypeScript interfaces from JSON samples.
Launch JSON to TypeScript Interface Generator
Text Tools
Text Diff Checker (Compare Text)
Compare two text blocks and highlight differences.
Launch Text Diff Checker (Compare Text)
Text Tools
Remove Extra Spaces / Clean Text
Clean up extra spaces and normalize plain text.
Launch Remove Extra Spaces / Clean Text
Developer Tools
Base64 Encoder
Encode plain text to Base64 instantly.
Launch Base64 Encoder
Developer Tools
Base64 Decoder
Decode Base64 back to plain text.
Launch Base64 Decoder
Developer Tools
URL Encoder
Encode text into URL-safe format instantly.
Launch URL Encoder
Developer Tools
URL Decoder
Decode URL encoded strings back to plain text.
Launch URL Decoder
Security Tools
Strong Password Generator
Generate strong random passwords with customizable character rules.
Launch Strong Password Generator
Calculators
Percentage Calculator
Calculate percentages, increases, and decreases quickly.
Launch Percentage Calculator
Lightning fast
Tools open in seconds with optimized client-side performance.
Privacy first
Most utilities run in your browser, keeping your data with you.
No signup needed
Use essential tools instantly without creating an account.
Always improving
New tools and upgrades are shipped continuously.
Build faster with the right tools at your fingertips.
Save your favorites, discover new categories, and streamline your daily workflow.
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.