JSON Formatter / Beautifier
Format and beautify JSON instantly with proper indentation.
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Developer Tools
Format, convert, encode and generate developer-focused utilities.
Tools in this category
View All ToolsJSON Fixer
Auto-detect and fix common JSON formatting issues in real time.
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JSON Schema Validator
Validate JSON against a JSON Schema in the browser with clear errors and example templates.
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CSV to JSON Converter
Convert CSV data into structured JSON quickly.
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JSON to CSV Converter
Convert JSON arrays of objects (or a single object) into CSV.
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CSV to TSV Converter
Convert comma-separated values (CSV) into tab-separated values (TSV).
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TSV to CSV Converter
Convert tab-separated values (TSV) into comma-separated values (CSV).
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JSON to TypeScript Interface Generator
Generate TypeScript interfaces from JSON samples.
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Base64 Encoder
Encode plain text to Base64 instantly.
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Base64 Decoder
Decode Base64 back to plain text.
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URL Encoder
Encode text into URL-safe format instantly.
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URL Decoder
Decode URL encoded strings back to plain text.
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URL Parser & Analyzer
Break down any URL into protocol, domain, path, query params, and hash.
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JWT Decoder
Decode JWT header, payload, and signature parts instantly.
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JWT Encoder
Encode JWT header and payload JSON into a token.
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Regex Tester
Test regular expressions against sample text with live highlights, match list, and capture groups.
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SHA256 Hash Generator
Generate SHA256 hashes from text instantly in your browser.
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MD5 Hash Generator
Generate MD5 hashes from text instantly in your browser.
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SHA1 Hash Generator
Generate SHA1 hashes from text instantly with a fast client-side hashing engine.
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SHA224 Hash Generator
Generate SHA224 hashes from text instantly in your browser.
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SHA384 Hash Generator
Generate SHA384 hashes from text instantly with a fast browser-side hashing engine.
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SHA512 Hash Generator
Generate SHA512 hashes from text securely in your browser.
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SHA3-256 Hash Generator
Generate SHA3-256 hashes from text instantly in your browser.
Go to SHA3-256 Hash Generator
RIPEMD160 Hash Generator
Generate RIPEMD160 hashes from text instantly in your browser.
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HMAC Generator
Generate HMAC signatures with Web Crypto and crypto-es using a secret key and payload.
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UTM Builder
Generate trackable campaign URLs with UTM parameters and ready-to-copy output.
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QR Code Generator
Generate QR codes from text or links and download as PNG, SVG, or JPEG.
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Barcode Generator
Generate barcodes in multiple formats and export as PNG, SVG, or JPEG.
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Cron Schedule Generator
Build cron schedule expressions with an intuitive visual builder.
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JSON to Dart Model Generator
Generate Dart model classes with fromJson/toJson from JSON samples.
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JSON to Python Pydantic Model Generator
Generate Python Pydantic BaseModel classes from JSON samples.
Go to JSON to Python Pydantic Model Generator
JSON to Kotlin Data Class Generator
Generate Kotlin data classes with null safety and serialization annotations from JSON samples.
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JSON to Swift Codable Model Generator
Generate Swift Codable structs from JSON samples with CodingKeys support.
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JSON to Go Struct Generator
Generate Go struct definitions with JSON tags from JSON samples.
Go to JSON to Go Struct Generator
JSON to Zod Schema Generator
Generate Zod validation schemas with inferred TypeScript types from JSON samples.
Go to JSON to Zod Schema Generator
JSON to C# Class Generator
Generate C# classes with JSON property attributes from JSON samples.
Go to JSON to C# Class Generator
JSON to Java POJO Generator
Generate Java POJO classes with Jackson annotations from JSON samples.
Go to JSON to Java POJO Generator
HEX ↔ RGB ↔ HSL Converter
Convert colors between HEX, RGB, and HSL formats with a live color preview.
Go to HEX ↔ RGB ↔ HSL Converter
Color Palette Generator
Generate harmonious color palettes from any base color — complementary, analogous, triadic, and more.
Go to Color Palette Generator
Tailwind Palette Generator
Generate Tailwind CSS v4 color shades (50–950) from any base color with a ready-to-copy @theme snippet.
Go to Tailwind Palette Generator
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.
Some tools keep your latest input in browser local storage for convenience. You can clear inputs anytime, and browser data can be removed from site settings.