Encode & Decode
Base64 Instantly
Encode text, URLs or files to Base64 and decode Base64 strings back to plain text or images. 100% private — runs entirely in your browser.
📖 How to Use
⚡ Why Use This Base64 Tool?
100% Private
Everything runs in your browser — no data is sent to any server.
File Support
Encode images, PDFs and any file to Base64 data URIs.
URL-Safe Mode
Base64URL encoding replaces + and / with - and _ for safe URL use.
Image Preview
See encoded images rendered instantly before copying the data URI.
Mobile Friendly
Works perfectly on phones and tablets for quick on-the-go encoding.
Free & No Limits
No sign-up, no file size caps for reasonable use, no watermarks.
❓ Frequently Asked Questions
🔗 Related Tools
Base64 Encoder & Decoder: Convert Text, Files, and Tokens Instantly
Base64 shows up in more places than most people realize — embedding an image directly into CSS, decoding the payload of a JWT, or reading a basic authentication header. A Base64 encoder and decoder handles all of these conversions, including a URL-safe variant needed for tokens and file uploads.
What Base64 Actually Does
Base64 converts binary data into plain ASCII text using a set of 64 printable characters. It exists because many older systems — email, some APIs, certain text-only fields — can't reliably handle raw binary data, but can handle text. Base64 is not compression and not encryption: encoded output is actually about 33% larger than the original, and anyone can decode it instantly. It's purely a format conversion for compatibility.
Standard Base64 vs Base64URL
Standard Base64 uses + and / as two of its 64 characters, along with = for padding. Both + and / have special meaning inside URLs, so putting standard Base64 directly into a URL or filename can break things unless it's separately percent-encoded. Base64URL solves this by substituting - for + and _ for /, and typically omitting the trailing padding — making the result safe to use directly in a URL, filename, or JWT without further encoding.
Common Use Cases
- Decoding a JWT — JSON Web Tokens use Base64URL for their header and payload sections, so decoding one lets you inspect its contents (though this doesn't verify the token's signature).
- Embedding images as data URIs — a small image can be Base64-encoded and embedded directly in HTML or CSS, avoiding a separate file request, though this increases the file size of the embedding document.
- HTTP Basic Authentication — the Authorization header for Basic Auth is a Base64-encoded
username:passwordstring, which is easy to decode and should only ever be sent over HTTPS. - Passing binary data through text-only systems — certain older APIs, email attachments, and some database fields expect text, so binary content is Base64-encoded to fit.
Base64 Is Not Encryption
This is worth repeating because it's a common and risky misunderstanding: Base64 provides no security. It's a reversible, publicly known encoding scheme — anyone with a decoder (including this one) can read the original content instantly. Never use Base64 alone to protect passwords, tokens, or any sensitive data. If you need to protect data, use actual encryption instead, and treat anything Base64-encoded as visible to anyone who has it.
Limitations to Keep in Mind
- Base64-encoded output is roughly 33% larger than the original input, since it re-encodes 3 bytes of binary data as 4 characters of text — factor this in for large files or performance-sensitive contexts.
- Decoding invalid or malformed Base64 (incorrect padding, characters outside the valid set) will fail — the tool reports this rather than returning a corrupted result.
- Processing happens directly in your browser using JavaScript, so your data is never sent to or stored on a server, even for file uploads.
Related Tools You Might Need
If your Base64 payload is a JSON object once decoded, the JSON Formatter can format and validate it. For encoding a value that will live inside a URL rather than being Base64URL-safe, the URL Encoder/Decoder handles percent encoding instead.
Frequently Asked Questions
Is Base64 encoding secure?
No. Base64 is an encoding format, not encryption — it has no secret key and anyone can decode it instantly. It should never be used as a substitute for real encryption when protecting sensitive data like passwords or personal information.
Why does my Base64 string end with one or two = signs?
The = characters are padding, added when the input length isn't evenly divisible by 3 bytes. They ensure the encoded output has a consistent, decodable length. Base64URL typically omits this padding since it isn't required in that context.
When should I use Base64URL instead of standard Base64?
Use Base64URL whenever the encoded string will appear inside a URL, filename, or a system like JWTs that specifically expects it — the substituted characters avoid needing separate percent-encoding. Use standard Base64 for contexts like email attachments or data URIs where URL-safety isn't a concern.
Can I encode an image to Base64 and use it directly in CSS?
Yes — the resulting data URI can be used directly as a CSS background-image value or an HTML <img src>, avoiding a separate network request for small images. For larger images, this approach increases the size of the HTML or CSS file itself, so it's best reserved for small icons or images.
