Developer Tools Runs in your browser Max 10 MB

Free Online Base64 Encoder / Decoder

Encode and decode text strings and binary files to and from standard or URL-safe Base64 with UTF-8 Unicode support.

Plain Text Input

URL-safe

Base64 Output 0 chars

Direct Answer FreeDailyTools Base64 Converter encodes text, credentials, and binary files into Base64 format and decodes Base64 strings back to their original form. All encoding runs locally in your browser using native JavaScript APIs without server transmission. Supports UTF-8 strings, URL-safe variants, and file encoding up to 10 MB.

How to Use Base64 Encoder / Decoder

Select Mode: Choose whether you want to Encode text, Decode Base64, or convert a File into a Data URI.
Enter Content: Type or paste your text or upload a file into the active workspace tab.
Toggle URL-Safe Option: Optionally check 'URL-Safe Base64' to use '-' and '_' instead of '+' and '/'.
Copy or Download: Click 'Copy' to paste the resulting string into your codebase, or 'Download' to save as a text file.

Operational Limits & Specifications

Processing Tier	Client-Side (In-Browser Execution)
Max File Size	10 MB per file
Max Batch Quantity	Up to 1 files
Max Total Batch Size	10 MB total
Supported Formats	.txt, .bin, .jpg, .png, .pdf

Common Use Cases

Embedding Inline Images (Data URIs)

Convert small PNG, SVG, or JPEG icons into Base64 Data URIs to embed directly in CSS or HTML, eliminating HTTP requests.

HTTP Basic Authentication Headers

Encode username and password credentials into Base64 format for HTTP 'Authorization: Basic' request headers.

Binary Safe Data Transmission

Encode cryptographic signatures, tokens, or binary hashes for transmission across email and query parameters.

Decoding Webhook & API Payloads

Decode Base64-encoded event payloads received from services like GitHub, Stripe, or Twilio.

Technical Mechanics & Architecture

Text encoding uses TextEncoder to convert UTF-8 characters to raw Uint8Array byte sequences before encoding through the browser's native window.btoa() and window.atob() APIs. File encoding utilizes the FileReader readAsDataURL API to stream binary buffers directly in client RAM.

Comparison with Alternatives

Unlike desktop CLI commands (such as base64 -w 0) that behave differently across Linux, macOS, and Windows PowerShell, FreeDailyTools provides a cross-platform, Unicode-safe encoder with instant live decoding and zero server uploads.

Tips & Troubleshooting

Check 'URL Safe' when embedding Base64 strings in URL query parameters; it replaces '+' with '-' and '/' with '_' while omitting padding.
Our tool supports full UTF-8 Unicode characters (like emojis and multilingual text) without character corruption.
When creating Data URIs for images, remember to prefix the output with 'data:image/png;base64,' in your HTML/CSS.
You can drag and drop small binary files (up to 10 MB) directly into the workspace to encode them into Base64 strings.

Frequently Asked Questions

Does this Base64 tool support non-English characters and emojis?

Yes! We use native TextEncoder and TextDecoder streams with full UTF-8 byte mapping, preventing standard ASCII encoding crashes on emojis, Arabic, Cyrillic, Chinese, and other Unicode text.

What is URL-Safe Base64 (base64url)?

Standard Base64 contains '+' and '/' characters which carry special meaning in URLs and query strings. URL-safe Base64 substitutes '+' with '-' and '/' with '_', and omits trailing '=' padding.

Can I convert images and binary files to Base64 Data URIs?

Yes! Switch to the 'File → Data URI' tab and drop any image or file to generate an inline 'data:mime/type;base64,...' string.

Is Base64 an encryption algorithm?

No. Base64 is a binary-to-text encoding format, not encryption. Encoded strings can be decoded by anyone without a cryptographic secret.

What is the maximum string size supported?

Our client-side engine can encode and decode text strings and binary buffers up to 20 MB without server latency.

Are my encoded credentials safe?

Yes, all encoding and decoding execution happens locally in your browser session with zero server communication.

Last reviewed: October 25, 2026 Learn about our architecture in How we process your files and mathematical Methodology.