All In One Developer Utilities
Here You can Format JSON, beautify SQL, test regular expressions (RegEx), decode JWTs, generate UUIDs, compress images, test API's, and more.
Formatters & Validators
JSON Formatter
A JSON formatter and validator is a tool used to organize and troubleshoot a JSON code (JavaScript Object Notation)
SQL Formatter
Instantly beautify, restructure, and properly indent complex multi-line SQL queries (PostgreSQL, MySQL, SQLite, T-SQL).
XML Formatter
Format, beautify, and validate your XML documents with deep structure inspection.
HTML Formatter
Format, beautify, and clean up HTML with proper indentation and nested validation.
CSS Minifier & Beautifier
Optimize stylesheets for production or format minified CSS back to human-readable structures.
Encoders & Decoders
Base64 Tool
Safely convert plain text to URL-safe Base64 binaries, or reconstruct binary components back to readable UTF-8 strings.
URL Encoder
Encode text strings into standardized URL safe percent-encoding or safely decode nested URI query segments.
JWT Decoder
Disassemble, extract, and format JSON Web Token (JWT) headers, payloads, signatures, and verify lifetime timestamps.
Data Generators
UUID Generator
Generate highly-entropic globally unique identifiers (UUIDv4) in bulk for database keys and testing.
Hash Generator
Generate cryptographic verification digests instantly using offline MD5, SHA-1, SHA-256, and SHA-512 algorithms.
Mock Data Generator
Create realistic mock data (Names, Addresses, Phones, Emails across borders) exportable to CSV/JSON for DB testing.
Testing & Validation
General Utilities
Color Picker & Palette
Interactive color wheel and harmony palette generator (Hex, RGB, HSL) with offline color contrast calculation.
QR Code Generator & Editor
Generate high-definition customized QR Codes offline for texts, links, and credentials with customizable scales.
Cron Job Parser
Break down complex crontab expression formats into plain English intervals and plot the next 5 system execution times.
Markdown Editor & Preview
Live side-by-side Markdown writing space with rich rendering, syntax verification, and export controls.
Image Compressor & Preview
Reduce pixel grid weight offline using hardware-accelerated Canvas operations. Visually optimize and download WebP/JPEG files.
Mini Compiler & Playground
Run, compile, and evaluate Python (WASM), SQL database, JavaScript, and HTML/CSS/JS live. Includes interactive console logs and terminal models.
About One Developer Tools
One Developer Tools is a "programmer's Swiss Army knife" where we are constantly developing new tools to help developers in their daily work, as well as providing new tips on how each stage of development works using our free online tools, and also showing what each platform is for.
Formatters & Validators
JSON Formatter & Validator
A JSON formatter & validator is a tool designed to organize, correct, and test JSON (JavaScript Object Notation) data. It consists of:
Formatter: Transforms raw JSON code, without spacing or line breaks, into a hierarchical and indented structure. The formatter can also minify the code, making it compact.
Validator: This analyzes the JSON code, searching for syntax errors. If an error is found, the tool indicates the line of code and the reason for the failure. Our validation tool points out the error in real time, at the same time you press Ctrl+v in the text box without pressing a validate button.
SQL Formatter & Validator
An SQL Formatter is a tool that organizes, aligns, and standardizes SQL code, transforming confusing or compressed queries into readable blocks of text. It will only change the visual aesthetics of the code (spacing, line breaks, and capitalization), ensuring that the logic and the final result of the query in the database remain exactly the same.
Meanwhile, an SQL validator is a tool that will analyze the SQL code to check if it is correct and free of syntax errors before even executing it in a database; it will act as a "grammar checker".
XML Formatter
Our XML Formatter offers a complete solution for formatting and validating XML documents by performing a thorough structural inspection. XML is widely used in various systems, feeds, and enterprise configurations; its syntax is based on tags that can become extremely dense without proper indentation. This tool solves this problem by restructuring the code in a hierarchical and visually pleasing way. In addition to applying the ideal formatting, it validates the document to ensure that the tags function perfectly. This way, you avoid serious errors in production XML code, optimize reading time, and maintain perfectly clean, consistent, and error-free files.
HTML Formatter
The HTML Formatter is an ideal tool for web developers who need to format, read, and clean HTML code with indentation and nesting validation. Working with web pages can often result in files that are difficult to understand, especially when integrating different sources. With our tool, the raw HTML code will be reworked, into a logical and readable blocks that respect the structural hierarchy. The tool will quickly identify unclosed or misplaced tags, ensuring correct and standardized markup. With ultra-fast processing, it ensures that your page structure will remain impeccably organized, readable, ready for team collaboration, and rigorously compliant with standards.
CSS Minifier & Beautifier
CSS Minifier & Beautifier is a tool that optimizes Stylesheets for production or deminifies minified CSS into fully readable code documents. During development, maintaining well-indented CSS code is perfect for facilitating adjustments and the overall design of the site. But for real-world environments, it's strictly necessary to remove spaces and comments, reducing the file size to speed up page loading. Our tool performs both tasks masterfully (minifying and deminifying), that is, reducing bytes to ensure high performance or decoding compressed styles to perform rigorous audits, you will always have total control of your precious CSS files.
Encoders & Decoders
Base64
Our Base64 Tool allows you to convert plain text to secure Base64 binaries for URLs, or reconstruct Base64 binary components (the reverse method) into readable UTF-8 strings. The Base64 format is widely used in programming to encode binary data, such as images, documents, certificates, IDs, etc., into ASCII sequences easily transmitted via text-based protocols. Our Base64 tool quickly solves decoding problems, ensuring absolute effectiveness and no data loss. It is indispensable for working with digital signatures, email headers, various tokens, and the storage of complex and everyday modern applications.
URL Encoder / Decoder
A URL Encoder/Decoder are tools used to transform URL characters to be transmitted securely over the internet. Because URLs only accept a restricted set of standard ASCII characters, special symbols, accents, or spaces need to be converted to the standard received by the browser. Here you can encode the entire URL with all symbols (with :// or /) or just the text (name of links and directories) preserving the :// or / for a REST pattern.
JWT Decoder
Our JWT Decoder tool is designed to disassemble, extract, and format headers, payloads, and signatures of JSON Web Tokens, and it also verifies the expiration times. In web applications, JWTs are the definitive standard for secure authentication between independent parts of the system. Developers often need to debug tokens to confirm that permissions and embedded data are strictly correct. Our tool will quickly process the encoded string, visually separating it into its three structural components. This makes it very easy to verify the validity of the user session without needing extra scripts, maintaining agility, accuracy, and greater technical security for the system.
Data Generators
UUID Generator
The UUID Generator allows you to create globally unique identifiers in bulk, ideal for database keys and testing routines. Ensuring the uniqueness of distributed records is a constant challenge during development, and the UUIDv4 format prevents key collisions in modern microservices. Our UUID generation tool makes it possible to generate hundreds of random UUIDs with just one click, facilitating injection into SQL scripts, payloads, or various simulation scenarios. It's a fast, clean, and optimized solution, essential for ensuring total consistency and secure traceability in the records of your valuable business applications.
Hash Generator
Hash Generator is a solution for quickly generating cryptographic verification hashes using offline methods and essential algorithms such as MD5, SHA-1, SHA-256, and SHA-512. In digital development and security, calculating the hash of passwords or files is a constant routine. Our Hash Generator receives the text and applies calculations to generate a hexadecimal signature that is irreversible. As the entire processing occurs in the browser (using local JavaScript), sensitive information is never sent to remote servers, ensuring local privacy. It is the perfect tool for verifying data integrity, comparing information, validating records, or designing structured cache keys.
Mock Data Generator
The Mock Data Generator creates realistic simulated data—such as global names, addresses, phone numbers, and emails that are exportable to CSV, JSON, or SQL. When someone is building a new app, it's crucial to test the interfaces with concrete information. Instead of manually filling empty spreadsheets, this tool automates the creation of thousands of fake records that follow the international logic.
Testing & Validation
RegEx Tester
Our Regex Tester allows you to test regular expressions in real time, with match listing, capture groups, and custom replacements. Regular expressions are powerful tools, but notoriously are difficult to debug without a suitable environment. Our tool provides a possibility where you can enter your pattern and instantly see which parts of the text are matched. Capture groups are displayed in an organized manner, and the replacement functionality allows you to preview the final result before applying it to your code. Ideal for form validations, log parsing, data extraction, and text transformations.
API Tester
The API Tester, also known as Postman Lite, is an HTTP client that allows developers to make native requests such as GET, POST, PUT, and DELETE to interact with any RESTful API'ss without needing to install any software. After sending, it's possible to view the server responses with details about payloads, status codes, and response times. This tool was created to test routes, simulate backend integrations, and debug network connections. It supports the configuration of custom headers and request bodies, making it a lightweight and efficient alternative for inspecting APIs during development.
General Utilities
Color Picker & Palette
A color picker and a color palette are resources used to find, combine, and extract exact colors for a digital environment. A color picker is a tool that allows you to choose or identify a specific color on a screen. It provides the digital color code (such as #HEX or RGB), while a color palette is a set or collection of selected colors that harmonize with each other for use in a specific project. Here you can select the color you want and use its code (HEX, RGB, HSL), as well as check the color's accessibility in a text based on WCAG 2.1.
QR Code Generator
The QR Code Generator allows you to create high-definition, personalized QR codes for text, links, credentials, and much more. With adjustable scales and visual customization options, the tool ensures crisp, ready-to-use QR codes for printed materials, digital media, or marketing campaigns. Because it works entirely in the browser, without sending data to external servers, it's a secure option for generating QR codes with sensitive information, such as private URLs or authentication tokens. Offline generation also guarantees speed and availability even without a stable connection. Whether for business cards, digital menus, event materials, or system integrations, our QR Code Generator offers flexibility, quality, and practicality in a single, freely accessible tool.
Cron Job Parser
A cron job parser is a tool or library that reads and translates a "cron expression" (consisting of a line of text with 5 to 6 fields) into readable dates and times. It tells an operating system exactly when an automated task (job) should be executed.
A typical expression contains 5 or 6 time fields:
1. Second (0-59)
2. Minute (0-59)
3. Hour (0-23)
4. Day of the month (1-31)
5. Month (1-12)
6. Day of the week (0-6, where 0 is Sunday)
Markdown Editor & Preview
Markdown Editor & Preview offers a side-by-side writing space with real-time rendering, syntax checking, and export controls. Writing documentation, READMEs, technical articles, and notes in Markdown is a common practice in the development ecosystem, and this tool makes the process more fluid and visual. With synchronized preview, you see exactly how the content will render as you write, eliminating surprises at publication. Syntax checking ensures your Markdown is well-structured, and export controls allow you to save content in different formats. Whether for contributions to open-source projects, corporate wikis, or creating technical content, Markdown Editor is a lightweight, efficient, and indispensable tool in the modern workflow.
Image Compressor & Preview
The Image Compressor & Preview is a tool to reduces image size using hardware-accelerated operations with the Canvas API. With an integrated comparative preview, it's possible to visually assess the quality of the compressed image before downloading it in WebP or JPEG format. Local compression ensures that images with sensitive data are never sent to external servers, offering complete privacy and security. It's the ideal tool for optimizing assets for websites, mobile applications, and content systems, reducing page load times without compromising the user's visual experience. Developers, designers, and content creators will find in this tool a quick and free solution to one of the biggest performance challenges on the modern web.
Mini Compiler & Playground
The Mini Compiler & Playground is an development environment that allows you to compile, run, and evaluate code in Python (via WASM), SQL, JavaScript, and HTML/CSS/JS directly in your browser. With an interactive log console and terminal templates, you can experiment with logic, test algorithms, and prototype solutions without needing to configure local environments. Ideal for learning, rapid prototyping, and demonstrations, the playground eliminates the entry barrier for those who want to instantly experiment with code. It supports multiple languages in a unified interface, making it versatile for different user profiles. Whether running Python scripts, testing SQL queries, debugging JavaScript, or viewing rendered HTML, the Mini Compiler offers a safe, fast, and accessible environment to explore and learn.