Free Developer Tools: Encode, Format and Generate IDs in Your Browser

Developer work often involves small, exact jobs: encoding a piece of text, checking a hash, formatting a block of JSON, generating a password, encoding a URL, or creating a unique identifier. This guide covers six free tools for those jobs: Base64 Encoder / Decoder, Hash Generator, JSON Formatter & Validator, Password Generator, URL Encoder / Decoder and UUID Generator.

All six tools covered in this guide are free with no sign-up, and they run in your browser. Each tool page shows its own steps, and the sections below follow those steps.

Tools in this guide

• Base64 Encoder / Decoder – encode text to Base64 or decode Base64 back to text.
• Hash Generator – generate MD5 and SHA-256 hashes from any text.
• JSON Formatter & Validator – format, indent and validate JSON, with clear error messages.
• Password Generator – generate a strong random password with the length and character types you choose.
• URL Encoder / Decoder – encode text or URLs for safe use in links, or decode an already-encoded URL string.
• UUID Generator – generate one or many random, valid version-4 UUIDs.

Base64 Encoder / Decoder

Base64 Encoder / Decoder encodes text to Base64 or decodes Base64 back to text, entirely in the browser. It supports full Unicode, so text with characters beyond basic letters and numbers can be encoded as well.

How to use it:

1. Paste or type your text into the box.
2. Click Encode to Base64 to convert text to Base64, or Decode from Base64 to reverse it.
3. Copy the result with one click.

Use this tool when a value needs to be carried as plain text, for example when embedding data in a text field that cannot safely hold the original characters.

Hash Generator

Hash Generator generates MD5 and SHA-256 hashes from any text, entirely in the browser. A hash is a fixed-length fingerprint of the input: the same input always gives the same hash, but the original text cannot be recovered from the hash.

How to use it:

1. Paste or type the text you want to hash.
2. Click Generate Hashes to compute the MD5 and SHA-256 values.
3. Copy either hash with its Copy button.

Use this tool when you want a quick fingerprint for a piece of text, for example to compare two versions of a value without sharing the value itself.

JSON Formatter & Validator

JSON Formatter & Validator formats, indents and validates JSON, with clear error messages. It runs entirely client-side and handles large JSON payloads.

How to use it:

1. Paste your JSON into the box.
2. Click Format to pretty-print it, or check the validity message.
3. Copy the formatted result.

Use this tool when a block of JSON is hard to read, for example a single-line response copied from an API or a log file, and you want it laid out with indentation.

Password Generator

Password Generator generates a strong random password with the length and character types you choose. Its controls include a length slider and checkboxes for Uppercase (A-Z), Lowercase (a-z), Numbers (0-9) and Symbols. Passwords are generated locally and are never sent to a server.

How to use it:

1. Choose a length and which character types to include.
2. Click Generate to create a password.
3. Copy it, or generate another.

Use this tool when you need a new password for an account or service and want it to be random rather than something you made up yourself.

URL Encoder / Decoder

URL Encoder / Decoder encodes text or URLs for safe use in links, or decodes an already-encoded URL string, in the browser. It uses standard percent-encoding, and runs entirely client-side, so nothing is sent to a server.

How to use it:

1. To encode: paste your text or URL and click Encode URL.
2. To decode: paste the encoded string and click Decode URL.
3. Copy the result with the Copy Result button.

Use this tool when a link contains spaces or special characters that need to be encoded before the link will work, or when you receive an encoded string and want to read it as plain text.

UUID Generator

UUID Generator generates one or many random, valid version-4 UUIDs in the browser, using a secure random source. It supports generating up to 50 UUIDs at once, with optional hyphen and uppercase formatting.

How to use it:

1. Use the slider to choose how many UUIDs you want.
2. Optionally toggle hyphens or uppercase formatting.
3. Click Generate UUID, then copy the result.

Use this tool when you need unique identifiers, for example for test data, database records or items in a list that need a distinct ID each.

Which tool should you use?

• To convert text to Base64, or back again: Base64 Encoder / Decoder.
• To get the MD5 or SHA-256 hash of a piece of text: Hash Generator.
• To format or check JSON: JSON Formatter & Validator.
• To create a strong random password: Password Generator.
• To encode or decode a URL string: URL Encoder / Decoder.
• To create random version-4 UUIDs: UUID Generator.

The tools also work in sequence: format a block of JSON with JSON Formatter & Validator, then encode the result with Base64 Encoder / Decoder if it needs to travel inside another text value.

Practical tips

• Base64 is encoding, not encryption: do not use it to protect sensitive data.
• For hashes, use SHA-256 where security matters; MD5 is faster but is not considered cryptographically secure for sensitive data.
• Copy hashes exactly: even a tiny change to the input produces a completely different hash.
• For passwords, use at least 12-16 characters for important accounts, store generated passwords in a password manager rather than plain text, and use a different password for every account.
• When encoding a URL, encode individual parameter values rather than the whole URL, to avoid encoding characters that are part of the URL structure.
• If decoding a URL fails, check that the text is actually percent-encoded, meaning it contains a percent sign followed by two characters.
• For UUIDs, remove hyphens if a system expects a compact 32-character format, and generate many at once when seeding test data.

Limitations to keep in mind

• Base64 encoding does not protect sensitive data; anyone can decode it just as easily as you encoded it.
• Hashes are one-way: you cannot recover the original text from a hash, so keep the original if you still need it.
• Formatting JSON does not fix invalid JSON; if the validity message reports an error, you still need to correct it in the original text.
• A generated password is only as safe as where you store it, and because passwords are generated locally and not sent to a server, a password you lose cannot be recovered from the tool.
• Version-4 UUIDs are random, not sequential or meaningful, so they do not sort in creation order or carry any information about the item they identify.
• URL encoding follows standard component encoding, so encoding a whole URL can change characters that are part of the URL structure.

FAQs