Base64 Encoder/Decoder

Encode and decode Base64 strings instantly

The Base64 Encoder/Decoder converts UTF-8 text to standard Base64 and back again in your browser. It is useful for debugging headers, embedded strings, and encoded payloads, and it also shows simple size stats so you can see the overhead Base64 adds. Everything runs locally, with no server round-trip.

Content reviewed: August 27, 2026

Encrypted with HTTPSProcessed in your browserFree to use

All processing runs locally in your browser. Your files and text are not sent to Tool-web's server.

Actions:

How to Use

Paste plain text or a Base64 string into the input box
Choose Encode or Decode mode
Review the processed output and the size stats below it
Copy, download, share, or swap the result back into the input if you need another pass

Features

Standard Base64 encode and decode modes
UTF-8 text support
Live processing after a short debounce plus manual action button
Copy, download, share, swap, and reset controls
Character and byte counts for both input and output

Tips for getting Base64 Encoder/Decoder right

Remember Base64 encodes but doesn't hide — don't treat it as security
Expect the encoded output to be about a third larger than the input
Normalize URL-safe Base64 manually before decoding if the source came from a JWT or URL parameter
Trim stray whitespace from pasted data before decoding to avoid errors

Worked example: build an HTTP Basic auth header

Enter `username:password` in Encode mode and copy the Base64 output into your `Authorization: Basic ...` header. If you later need to inspect a captured value, swap to Decode mode and paste the Base64 string back in to confirm the original credentials format.

Standard Base64 vs URL-safe Base64

This tool produces standard Base64 output with `+`, `/`, and padding when needed
JWTs and some URLs often use the Base64URL variant instead
If a Base64URL value fails to decode, convert `-` to `+`, `_` to `/`, and restore missing padding first
Base64 changes representation, not security — encoded data is still readable after decoding

Real-World Use Cases

Encoding credentials or tokens for debugging workflows
Decoding Base64 payloads from logs or browser tools
Inspecting text blobs embedded in APIs or config files
Preparing plain text for transmission through text-only channels
Checking how much Base64 increases the size of a payload

Best Practices

Treat Base64 as representation only, not as protection
Trim obvious whitespace before decoding copied values
Verify a decoded result matches the original source before using it in production debugging
Keep an eye on the byte counts when Base64 size matters
Use Swap when you want to decode what you just encoded or vice versa without repasting

Common Mistakes to Avoid

Confusing Base64 encoding with encryption
Pasting a Base64URL string into the decoder without normalizing it first
Forgetting that Base64 expands the payload size
Mixing up encode and decode mode before copying the result
Trying to use this text-only tool for file encoding workflows

Troubleshooting

If decoding fails, check for invalid characters or missing padding
If a JWT-like value fails, normalize the Base64URL characters before decoding
If text looks corrupted, confirm the original source was UTF-8 text
Use Reset when you have switched modes several times and want a clean start
Make sure you are pasting plain text rather than a binary file dump

Frequently Asked Questions

What is Base64?

Base64 is an encoding scheme that represents binary data as ASCII text, commonly used for transmitting data over text-based protocols.

Does it support Unicode?

Yes. The tool handles UTF-8 encoded text including non-ASCII characters.

Can I encode files?

No. This tool works with text input only. For file-based workflows, use a file-specific encoder such as the Image to Base64 tool.

Privacy & Security

Base64 encoding and decoding happens entirely in your browser. No data is transmitted to any server. However, remember that Base64 is not encryption — it provides no privacy protection.

Tips & Best Practices

Remember Base64 encodes but doesn't hide — don't treat it as security
Expect the encoded output to be about a third larger than the input
Normalize URL-safe Base64 manually before decoding if the source came from a JWT or URL parameter
Trim stray whitespace from pasted data before decoding to avoid errors

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Tips for getting Base64 Encoder/Decoder right

Remember Base64 encodes but doesn't hide — don't treat it as security

Expect the encoded output to be about a third larger than the input

Normalize URL-safe Base64 manually before decoding if the source came from a JWT or URL parameter

Trim stray whitespace from pasted data before decoding to avoid errors

Standard Base64 vs URL-safe Base64

This tool produces standard Base64 output with `+`, `/`, and padding when needed

JWTs and some URLs often use the Base64URL variant instead

If a Base64URL value fails to decode, convert `-` to `+`, `_` to `/`, and restore missing padding first

Base64 changes representation, not security — encoded data is still readable after decoding

Best Practices

Treat Base64 as representation only, not as protection

Trim obvious whitespace before decoding copied values

Verify a decoded result matches the original source before using it in production debugging

Keep an eye on the byte counts when Base64 size matters

Use Swap when you want to decode what you just encoded or vice versa without repasting

Troubleshooting

If decoding fails, check for invalid characters or missing padding

If a JWT-like value fails, normalize the Base64URL characters before decoding

If text looks corrupted, confirm the original source was UTF-8 text

Use Reset when you have switched modes several times and want a clean start

Make sure you are pasting plain text rather than a binary file dump