How to Encode and Decode Base64
- 1
Choose your mode
Select "Encode" to convert text or files into Base64 format, or "Decode" to convert a Base64 string back to its original form.
- 2
Enter or paste your input
Type text directly, paste a Base64 string, or drag and drop a file (images, PDFs, documents up to 10 MB). Select the appropriate mode: Text, File, or URL-Safe.
- 3
Get the result instantly
The encoded or decoded output appears after you click the Encode or Decode button. For file encoding, the full Base64 data URI is generated, ready to embed in HTML, CSS, or JSON.
- 4
Copy or download the output
Click "Copy" to grab the result for pasting into code, or download the decoded file directly to your computer. The copy button handles strings of any length.
A Developer Tool That Respects Your Data
Text & File Support
Encode plain text strings or entire binary files (images, PDFs, fonts). File encoding produces a proper data URI with the correct MIME type for direct embedding.
URL-Safe Encoding
Optionally produce URL-safe Base64 that replaces + and / with - and _, making the output safe for query parameters, filenames, and JWT tokens without additional escaping.
Fully Client-Side
All encoding and decoding happens in your browser using native JavaScript APIs. Your data never leaves your machine, which matters when handling API keys, tokens, or sensitive payloads.
Encoding History
Recent encode/decode operations are saved locally in your browser so you can quickly revisit previous conversions without re-pasting the input.
Data URI Generation
Automatically prepends the correct data:mime/type;base64, prefix when encoding files, producing a ready-to-use data URI for HTML img tags, CSS backgrounds, or email templates.
Real-Time Preview
Output is displayed in a text area ready to copy. For file encoding, the Base64 data URI is generated for direct use in HTML or CSS.
Where Base64 Shows Up in Real Work
Web developers embed small images and icons as Base64 data URIs to reduce HTTP requests. Instead of loading a separate PNG for a tiny logo or icon, you encode it directly into your HTML or CSS. This technique is especially effective for email templates where external image hosting is unreliable and many email clients block remote images by default.
Backend developers and API integrators encounter Base64 constantly. JWT tokens are Base64-encoded JSON. HTTP Basic Authentication headers encode credentials in Base64. Many APIs accept file uploads as Base64 strings in JSON payloads. Having a quick way to decode a JWT to inspect its claims, or encode an image for an API request, is a daily workflow need.
Security researchers and IT professionals decode Base64 strings found in logs, email headers, and configuration files to understand what data is being transmitted. Malware payloads, obfuscated scripts, and encoded attachments all use Base64. Being able to decode them quickly in a trusted client-side tool is safer than using random websites that might log your input.
Frequently Asked Questions
Is Base64 a form of encryption?
No. Base64 is an encoding scheme, not encryption. It converts binary data to ASCII text for safe transport but provides zero security. Anyone can decode a Base64 string instantly. Never use Base64 alone to "hide" passwords, tokens, or sensitive data.
Why does Base64 make files about 33% larger?
Base64 represents every 3 bytes of binary data as 4 ASCII characters. This 4:3 ratio means the encoded output is always roughly 33% larger than the original. For small assets like icons this is acceptable, but for large files the size overhead makes Base64 impractical.
What is the difference between standard and URL-safe Base64?
Standard Base64 uses + and / characters, which have special meaning in URLs and filenames. URL-safe Base64 replaces them with - and _, and often omits trailing = padding. JWTs and many modern APIs use URL-safe encoding by default.
What is the maximum file size I can encode?
This tool supports files up to 10 MB. While there is no theoretical Base64 size limit, very large files produce massive strings that are slow to process in a browser and impractical to embed. For files over a few hundred KB, direct binary transfer is usually better.
Can I decode a JWT token with this tool?
You can decode the individual Base64 segments of a JWT (header and payload) to read their JSON contents. However, for full JWT inspection including signature verification and expiration checking, use a dedicated JWT decoder tool which parses all three segments automatically.
Related Tools
Password Generator
Generate secure passwords and API keys that you might need to Base64-encode for config files.
QR Code Generator
Encode Base64 data URIs into QR codes for easy transfer between devices.
Storage Unit Converter
Calculate how much larger your data will be after Base64 encoding.
Is This Link Safe?
Verify URLs you decode from Base64 strings before visiting them.