🔡 Base64 Encoder & Decoder
Encode text to Base64 or decode Base64 strings instantly. Supports file uploads, UTF-8 text, and URL-safe encoding. Free, private, no signup.
What is a Base64 Encoder?
A Base64 encoder converts binary data or plain text into a 64-character ASCII string using letters, numbers, + and / symbols. This tool runs entirely in your browser — nothing is uploaded to any server. Developers rely on Base64 encoding to safely transmit binary data through text-only channels like HTTP headers, JSON payloads, and email attachments. This Base64 encoder supports full UTF-8 text and binary file input.
How to Use This Base64 Encoder
Using this Base64 encoder is straightforward. Select the Encode tab, paste your text or click File to upload any file, and the Base64 encoder instantly produces the encoded output. To decode, switch to the Decode tab, paste your Base64 string, and the result appears immediately. Enable the URL-safe toggle to replace + with - and / with _, removing padding — this Base64 encoder output is safe to use in URLs and filenames.
Base64 Encoder for Developers and APIs
REST APIs frequently require Base64 encoding for Basic Authentication headers (username:password encoded), embedding images in HTML or CSS as data URIs, and transmitting binary data in JSON or XML. This Base64 encoder handles all these scenarios. When building authentication flows, encoding credentials with a reliable Base64 encoder saves debugging time. File uploads to APIs that expect base64-encoded payloads are handled directly — upload the file and copy the output.
URL-Safe Base64 Encoding
Standard Base64 uses + and / characters that break URLs when passed as query parameters. This Base64 encoder's URL-safe mode replaces + with - and / with _ and removes padding characters, producing a string safe for use in URLs, cookies, and JWT tokens. Toggle URL-safe encoding before generating output when your target is a web URL or filename — the result is JWT and cookie-safe in one click.
When to Use Base64 Encoding
Base64 encoding is essential when transferring binary data through text-only channels. Common use cases include embedding fonts and images in CSS (data URIs), sending binary file attachments in email via MIME encoding, storing binary data in JSON or XML fields, and passing credentials in HTTP Authorization headers. A Base64 encoder is not encryption — it offers no security by itself. For sensitive data, encrypt first, then encode the result for transmission. This free online Base64 encoder handles all standard encoding tasks instantly.
Email protocols like SMTP were originally designed for ASCII text only. When you attach a file to an email, your client encodes the binary content using Base64 encoding and wraps it in a MIME block with a content-type header — this is how PDF files, spreadsheets, and image attachments travel reliably through text-based mail infrastructure without corruption. In CSS, the data: URI scheme embeds small images and fonts directly inside a stylesheet as a Base64-encoded string, eliminating a separate HTTP request per asset. A loading spinner, site icon, or inline SVG can be embedded this way, improving page performance for small resources. JSON Web Tokens (JWTs) structure every token as three dot-separated segments — the header, the payload, and the signature. The first two are Base64url-encoded JSON objects, which is why you can paste any JWT into a decoder and immediately read the algorithm, expiry, and claims without needing the signing key.
- Encode images to data URIs for inline CSS or HTML
- Generate Base64 credentials for HTTP Basic Authentication headers
- Encode file attachments for email MIME or API payloads
- URL-safe mode for JWT tokens, cookies, and query parameters
- Decode Base64 strings from APIs or JWT token payloads
Frequently Asked Questions
What is a Base64 encoder?
A Base64 encoder converts binary or text data into a 64-character ASCII representation using A-Z, a-z, 0-9, + and /. It is used to safely transmit binary data through text-based protocols that cannot handle raw binary bytes.
How does this Base64 encoder work?
Paste your text or upload a file, select Encode or Decode, and the result appears instantly. For text, the tool uses TextEncoder to handle UTF-8 correctly before encoding. For files, it reads the binary data via FileReader and converts it to base64 using the browser's built-in btoa() function.
What is URL-safe Base64?
URL-safe Base64 replaces + with - and / with _ and removes trailing = padding. This makes the encoded string safe to include in URLs, filenames, cookies and JWT tokens without percent-encoding. Toggle URL-safe mode in this tool before encoding.
Can I encode files with this Base64 encoder?
Yes. Click the File button to select any file from your device. The tool reads it as binary data and converts it to a Base64 string. This works for images, PDFs, documents or any file type. Nothing is uploaded — all processing happens in your browser.
Is this Base64 encoder free?
Yes, completely free with no signup, no file size limit displayed (browser memory is the limit), and no data sent to any server. All encoding and decoding runs in your browser using native JavaScript APIs.
Is Base64 encoding the same as encryption?
No. Base64 is an encoding scheme, not encryption. Anyone with the Base64 string can decode it instantly. If you need to protect sensitive data, encrypt it first with a proper algorithm, then encode the result.