Top Free Online Tools for Developers: JSON Formatter, Regex Tester, JWT Decoder, and Over 40 Tools to Speed Up Your Workflow

Every day, I and other developers handle countless types of data, configurations, and encryptions. Sometimes you need to format a JSON string received from an API, other times you have to test a complex regular expression (regex). Or simply decode a JWT to read its payload. Though small, these tasks are essential in our work.

The Real Challenge: Racing Against Time with Small Bottlenecks

I often see colleagues (and myself) opening dozens of browser tabs to search for “JSON formatter online” or “regex tester free.” Each time, it causes us to lose focus and wastes time searching. Sometimes, we even encounter websites full of ads or unreliable sources.

I once saw a junior developer confused when needing to decode a JWT. They used an unfamiliar tool and accidentally pasted a token containing sensitive customer information into it. Fortunately, no incident occurred. However, this made me think a lot about security and work efficiency.

Why Small Tools Cause Big Problems?

• Scattered and Inconsistent: There’s no single reliable, centralized location. Each tool resides on a different website, with varying interfaces and usage. Getting familiar with each small tool from scratch also consumes time.
• Security Risks: Many online tools require sending data to a server for processing. This is extremely dangerous if you’re working with sensitive project or client data. Who can guarantee that your data won’t be stored or misused?
• Reduced Productivity: Constantly switching between tabs and different tools interrupts the workflow. Time that should be spent on writing code or solving major problems is fragmented by these small, scattered tasks. A study by the University of California, Irvine, indicates that it takes an average of 23 minutes for a person to return to work after being interrupted.
• Internet Dependency: Some desktop tools can solve this problem. However, they are not always convenient to carry or install on every computer you use.

Common Solutions and Their Limitations

Faced with these issues, developers often resort to a few solutions. However, each has its own limitations:

• Using individual tools on separate websites: This is the most common approach. Easy to find, but high security risks and significantly reduced work efficiency.
• Using IDE extensions: Very convenient for tasks deeply integrated into the coding process. For example: code formatting. However, not every tool has a corresponding extension. Or the extension might not be powerful/flexible enough to meet all needs.
• Writing your own scripts or small tools: Great if you have the time and want full control. But with over 40 different tools, coding each one individually is not feasible. When I first started working, I tried writing a small script to format JSON. But it only met a few simple cases and quickly became outdated when requirements changed.
• Using specialized desktop applications: Powerful and secure. However, they often come with a cost, consume system resources, and are not always available on every operating system or computer I’m working on.

Optimal Solution: A Multi-functional, Secure, and Convenient “Tool Workshop”

Given these challenges, I’ve always sought a comprehensive solution. A place where I can find all the necessary small tools, centralized in one location, while ensuring security and performance.

And I discovered ToolCraft – an online collection of over 200 free tools, including more than 40 specifically for developers. I’m truly impressed with its quality and convenience.

What I like most about ToolCraft is that all tools run 100% in the browser (client-side). This means your data is never sent to ToolCraft’s servers. All processing happens directly on your computer. This ensures absolute privacy and security for sensitive information. I feel very confident using it to process JWTs or JSONs containing customer data.

In my most recent web app project with 5 developers, I implemented ToolCraft and noticed a significant increase in productivity. Instead of each person fumbling to find their own tools, I introduced ToolCraft to the entire team. With just one link, the whole team shares a standardized set of tools. This significantly reduces context-switching time and risks.

Explore the “Must-Have” Tools on ToolCraft

I’ll delve into some of the tools I use most frequently to help you better understand their value:

1. JSON Formatter & Validator

JSON data from APIs often returns as long, unreadable strings or with syntax errors. This JSON Formatter & Validator tool helps me format JSON beautifully, with color, making it easy to read. If there’s a syntax error, it even points out the location of the error. This significantly speeds up debugging.

Example:

{"name":"John Doe","age":30,"isStudent":false,"courses":[{"title":"Math","grade":"A"},{"title":"Physics","grade":"B"}]}

After passing through this tool, it will look like this:

{
  "name": "John Doe",
  "age": 30,
  "isStudent": false,
  "courses": [
    {
      "title": "Math",
      "grade": "A"
    },
    {
      "title": "Physics",
      "grade": "B"
    }
  ]
}

2. Regex Tester

Regular expressions are powerful yet often “tricky” tools. Just one incorrect character can break the entire pattern. With the Regex Tester, I can test regular expressions in real-time against test strings. It clearly displays match groups and supports flags like g (global), i (case-insensitive), m (multiline). This helps me build and debug regexes extremely effectively.

Example:

Pattern: /\b\d{3}-\d{2}-\d{4}\b/g
Text: "My social security number is 123-45-6789. Another one: 987-65-4321."
Match 1: 123-45-6789
Match 2: 987-65-4321

3. JWT Decoder

When working with JWT-based authentication systems, inspecting the contents of a token is crucial. It helps ensure that user permissions and information are transmitted correctly. The JWT Decoder helps me quickly decode a JWT. I can view the header, payload (which usually contains user information and permissions), and even the signature. From there, I can verify the token’s validity. This is extremely useful when debugging authentication-related issues.

Example (sample data):

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

The decoding result will display:

• Header: {"alg": "HS256", "typ": "JWT"}
• Payload: {"sub": "1234567890", "name": "John Doe", "iat": 1516239022}
• Signature Verification: (Will usually indicate valid/invalid if a secret key is provided)

4. Base64 Encoder/Decoder

Sometimes I need to encode or decode text strings or binary data to Base64. The purpose is to safely transmit them through channels that don’t directly support binary data. For example: embedding small images into CSS. The Base64 Encoder/Decoder provides fast Base64 encoding and decoding capabilities, supporting both text and file uploads.

Example:

Original Text: "Hello, World!"
Base64 encode: "SGVsbG8sIFdvcmxkIQ=="

Base64 decode: "SGVsbG8sIFdvcmxkIQ=="
Original Text: "Hello, World!"

5. UUID Generator

Do you need to generate Unique Universal Identifiers (UUIDs) for database objects, session IDs, or temporary IDs? The UUID Generator helps create UUID v4s extremely quickly. You can generate a batch of UUIDs with just one click. This is convenient for creating sample data or assigning IDs.

Example:

9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d
e0d7c7b8-f1a2-4c6e-8d9f-0a1b2c3d4e5f

6. URL Encoder/Decoder

Special characters in URLs need to be encoded (percent-encoding) to avoid conflicts or misinterpretation when transmitted over the network. Sometimes, decoding is necessary to read a complex URL. The URL Encoder/Decoder performs this task simply. It helps me easily handle query parameters or encoded URLs.

Example:

Original URL: "https://example.com/search?query=hello world&param=cần mã hóa"
URL encode: "https://example.com/search?query=hello%20world&param=c%E1%BA%A7n%20m%C3%A3%20h%C3%B3a"

7. Hash Generator

Generate hash codes (MD5, SHA-256, etc.) to check file integrity (checksum) or sometimes to hash passwords before storing them in a database. (Note: absolutely do not use MD5/SHA-1 for production passwords; use bcrypt instead!). With the Hash Generator, I can quickly generate common hash codes. It even allows comparing them to verify files.

Example:

Text: "itfromzero.com"
MD5: 23d8c1e9f2a7a4b0c5d6e7f8a9b0c1d2
SHA256: 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1f367728a1be02d53e4cdc2f1a

8. YAML ↔ JSON Converter

Configuration files often use YAML format, but when interacting with APIs or web applications, JSON is more common. Converting between these two formats is necessary. The YAML ↔ JSON Converter helps me quickly convert between YAML and JSON, preserving data structure.

Example (YAML to JSON):

# YAML
name: John Doe
age: 30
isStudent: false

// JSON
{
  "name": "John Doe",
  "age": 30,
  "isStudent": false
}

Conclusion: Optimize Your Workflow, Master Your Tools

In the IT industry, time and accuracy are key factors. Owning a reliable, convenient, and secure set of tools like ToolCraft not only saves me hours each week but also enhances work quality and minimizes security risks.

I believe that any developer, from newcomers to experienced system architects, can benefit. Integrate these tools into your daily workflow. Give ToolCraft a try; I don’t think you’ll be disappointed.