Base64 Encoder & Decoder - Instant Conversion Free Online
Encode text or files to Base64, or decode Base64 strings back to original content. Supports text, images, and binary files. Free, instant, fully private.
About Base64 Encoder & Decoder
Encode and decode Base64 strings instantly with Convertify. Convert text, files, and images to and from Base64 encoding for embedding data in HTML, CSS, JSON, and API payloads. Our tool supports standard Base64 and URL-safe Base64 variants, handling large inputs efficiently with real-time encoding and decoding preview.
Why Use Convertify's Base64 Encoder & Decoder?
Encode + Decode
Two-way conversion in one tool
Files or Text
Drag a file or paste a string
Browser-Only
Nothing leaves your device
Big Inputs OK
Handles long strings without lag
Common Use Cases
- 1Embedding images as Base64 data URIs in HTML and CSS files
- 2Encoding API authentication tokens and credentials
- 3Decoding Base64 strings from API responses for debugging
- 4Converting binary file content for JSON payload transmission
- 5Generating Base64 encoded email attachments for MIME messages
- 6Encoding configuration data for environment variables
- 7Debugging encoded strings in JWT tokens and cookies
Convertify processes all files directly in your browser — nothing is uploaded to any server. Your documents stay private and secure on your device at all times.
The complete guide to Base64 Encoder/Decoder
Last updated June 1, 2026Base64 encoding converts binary data (files, images, arbitrary bytes) into ASCII text — a sequence of letters, numbers, +, and / characters. This is essential for embedding binary data in text-based formats: JSON API payloads, HTML data URIs, email attachments (MIME), configuration files, and JWTs. Convertify's Base64 tool encodes and decodes text and files, with URL-safe Base64 support for tokens and query parameters.
Base64 is not encryption — it's encoding. Base64-encoded data is trivially reversible by anyone who knows it's Base64. Never use it as a security measure. Use it when you need to safely embed binary data in a context that only accepts text (the name comes from each 6-bit group being represented as one of 64 printable characters).
How Base64 Encoder/Decoder on Convertify compares
| Feature | Convertify | Typical online tool |
|---|---|---|
| Files uploaded | Never | Text only |
| File encoding | Yes (binary files) | Text strings only |
| URL-safe mode | Yes | Sometimes |
| Line break control | Yes | Fixed wrapping |
| Daily limit | Unlimited | Limited |
Step-by-step: how to use Base64 Encoder/Decoder
- 1
Choose mode: Encode or Decode
Encode converts text or file binary to a Base64 string. Decode reverses Base64 back to the original content.
- 2
Provide input
Paste text in the text area, or upload a file (image, PDF, any binary) for encoding. For decoding, paste the Base64 string.
- 3
Copy or download result
Encoded output is a text string — copy to clipboard for use in code, config files, or API calls. Decoded output downloads as the original file type.
Real-world scenarios
Embedding images in HTML or CSS
Use a base64-encoded data URI to embed small images directly in HTML/CSS without a separate file request: `<img src='data:image/png;base64,iVBORw0K...' />`. Best for small icons and thumbnails under 10 KB.
API authentication headers
HTTP Basic Auth encodes credentials as Base64: `Authorization: Basic base64(username:password)`. Developers testing API endpoints manually encode their credentials here before adding to the header.
JWT debugging
JSON Web Tokens (JWTs) have three Base64URL-encoded sections separated by dots. Decode the payload section to inspect the claims without needing a dedicated JWT debugger.
Email MIME attachments
MIME email encodes binary attachments as Base64 for transmission over text-based SMTP. Developers building email systems use Base64 encoding when constructing raw MIME messages.
Troubleshooting and edge cases
My decoded output looks garbled.⌄
Base64 decodes binary data to its raw bytes. If the original was a binary file (image, PDF), the decoded output is binary — download it as a file rather than trying to read it as text. Use the 'Download as file' option.
I need URL-safe Base64 (no + or / characters).⌄
Standard Base64 uses + and / which break in URL query parameters. Enable 'URL-safe mode' to use - and _ instead (RFC 4648 Base64URL). JWT and OAuth tokens use URL-safe Base64.
The encoded string has line breaks — is that correct?⌄
MIME Base64 traditionally wraps every 76 characters with a line break (per RFC 2045). For use in JSON, HTML attributes, or code strings, use the 'No line breaks' output mode for a single continuous string.
How to Base64 Encode & Decode Free Online — Image & Text - Step by Step Guide
Input Data
Paste text or upload a file you want to encode or decode.
Choose Mode
Select Encode (to Base64) or Decode (from Base64).
Get Result
Copy the output or download the decoded file instantly.