What is URL-safe Base64?

URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _. This makes the string safe for URLs, filenames, and JSON without additional encoding.

When should I use URL-safe Base64?

Use URL-safe Base64 for JWT tokens, OAuth parameters, S3 signed URLs, filenames, and any context where +, /, or = cause issues.

Does URL-safe Base64 change the encoded data?

No. URL-safe Base64 encodes the same binary data, just with URL-friendly substitutions. Decoding restores the original exactly.

What is the difference between standard and URL-safe Base64?

Standard uses + and / with = padding. URL-safe uses - and _ without padding. Both represent the same binary data. Everything is processed locally in your browser, so your files never leave your device.

Is this tool free to use?

Yes. There is no charge, no account, and no watermark on the output. Everything is processed locally in your browser, so your files never leave your device. This keeps your data private and avoids waiting for server processing.

URL-Safe Base64 Encoder — Url Safe

URL-Safe Base64 Encoder

URL-safe Base64 (RFC 4648 §5) swaps +/ for -_ and drops padding — safe for JWT, URLs, and filenames. Use our tool to generate the Base64 instantly.

Why it matters: URL-safe Base64 (RFC 4648 §5) swaps +/ for -_ and drops padding — safe for JWT, URLs, and filenames.

How to convert an image to Base64 (and back)

1Choose Encoder to turn an image into Base64, or Decoder to turn a string back into an image.
2Pick your output — raw, URL-safe, no-padding, or wrapped — and decide whether to include the data: prefix.
3Copy to clipboard or download as a file. Everything runs locally — nothing is uploaded.

Best settings for this page: Upload an image, choose your output format, and copy or download the result.

All processing runs locally in your browser. Your images and strings are not uploaded to any server.

Base64 basics: size, data URIs, and when to use it

Size trade-off — Base64 inflates binary data by about 33%. It is best for small assets (icons, logos) and single-file pages; for large images, external files with caching are faster.

Data URI — a data URI is raw Base64 prefixed with a MIME type, e.g. data:image/png;base64,.... Include the prefix for HTML/CSS; store raw Base64 for JSON or databases.

URL-safe — RFC 4648 §5 swaps + and / for - and _ and drops padding, making the string safe for URLs, JWTs, and filenames.

Use it for embedding images in code, email, and APIs where an extra HTTP request is worse than the size cost.

Frequently Asked Questions

All Base64 Tools

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Decode

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URL-Safe Base64 Encoder

Output Settings

Image Preview

Base64 Output

Paste Base64 String

Decoded Image

Related reading

URL-Safe Base64 Encoder

How to convert an image to Base64 (and back)

Base64 basics: size, data URIs, and when to use it

Frequently Asked Questions

All Base64 Tools

Encode

Decode

Features

More Tools

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