Base64 Encoder / Decoder

Base64 Encoder and Decoder — Convert Text and Images Online

Base64 is an encoding scheme that converts binary data into a string of ASCII characters. It's used everywhere in web development and software systems — to embed images directly in HTML or CSS, to transmit files through APIs that only accept text, and to encode credentials for HTTP Basic Authentication. This tool encodes and decodes Base64 for both text and images.

How it works

Encoding converts your text or image into a Base64 string — a long sequence of letters, numbers, plus signs, and forward slashes that represents the original data. Decoding reverses this: take a Base64 string and get back the original text or image. The encoded form is always larger than the original (by about 33%) because you're representing binary data using only 64 safe ASCII characters.

Text encoding and decoding

Type or paste any text, and the encoder converts it to Base64. This is commonly used for: encoding API keys and credentials before including them in HTTP headers, encoding strings for storage in systems that don't support special characters, and testing that a Base64 string you received decodes to the expected value.

Image encoding

Upload an image and get a Base64 data URL — something like data:image/png;base64,iVBORw0KGgo.... You can paste this string directly into an HTML <img> tag's src attribute, embed it in CSS as a background-image URL, or include it in an email template. The image becomes self-contained — no separate file request needed.

Common use cases

Embedding small images in CSS: For small icons, logos, or loading spinners, embedding as Base64 eliminates an HTTP request. For images under 5–10KB, this is usually a net win for page performance. For larger images, the size overhead and reduced cacheability make separate files better.

API development and testing: REST APIs that accept file uploads sometimes expect the file content as a Base64-encoded string in a JSON field. Encode your test file here to construct the API request manually.

Email inline images: HTML emails can embed images as Base64 so they don't rely on external servers. This is useful for transactional email templates where the logo or signature image should always be visible regardless of whether the recipient's email client blocks external images.

Debugging encoded data: If you receive a Base64 string in a log, an API response, or a JWT token payload, decode it here to see the original content.

HTTP Basic Authentication: The Authorization header for HTTP Basic Auth is the username and password joined by a colon, then Base64 encoded. Encode your credentials here to construct a manual API request for testing.

Fintech and payment APIs in India: Several payment gateway APIs (Razorpay, PayU) and banking APIs send and receive certain fields as Base64-encoded data — particularly images for KYC documents or encrypted payloads. Decode those values here for debugging.

Tips

Don't use Base64 to "secure" sensitive data. Base64 is an encoding, not encryption — anyone can decode it in seconds. It's not a security measure; it's a way to represent binary data as text.

For large images, Base64 is not the right approach. The encoded string is 33% larger than the original file, and it can't be cached independently by the browser (the whole HTML or CSS file containing it must be re-downloaded when it changes). Use separate image files for anything that needs to be cached or that's larger than a small icon.

Limitations

This tool handles text and image files. Binary file types (ZIP, PDF, executable files) can technically be Base64 encoded but the tool may not preview the decoded result meaningfully — you'd just get the raw binary data back.

Very large images take a moment to encode because the browser needs to process the full file data. Files over a few megabytes may be slow or may hit browser memory limits on lower-end devices.