Base64 Encoder & Decoder

What this Base64 encoder & decoder does

Base64 encoding converts binary or text data into a 64-character ASCII alphabet, making it safe to transmit through systems that only handle plain text — email bodies, HTTP headers, JSON payloads, and URLs. This English-language version of the tool encodes any UTF-8 input to Base64 (RFC 4648) and decodes Base64 strings back to readable text, with full support for the URL-safe variant that replaces + and / with - and _. Unicode 15.1 added 627 new characters in 2023, including new CJK extensions and emoji — this tool handles all of them correctly by encoding UTF-8 bytes before applying Base64, avoiding the classic btoa() pitfall in JavaScript. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs. That matters when you're working with JWT tokens, Basic Auth credentials, or any encoded payload that shouldn't touch a third-party server.

Features

• Correct UTF-8 handling. Encodes multi-byte Unicode characters properly before applying Base64, so emoji, CJK characters, and accented letters all round-trip without data loss — unlike a bare btoa() call in JavaScript, which throws on non-Latin-1 input.
• URL-safe Base64 mode. Switches the output alphabet to use - and _ instead of + and /, and optionally strips padding (=). Use this when embedding Base64 in URLs, query strings, or JWT segments, where standard characters would need percent-encoding.
• Instant bidirectional conversion. Flip between the Encode and Decode tabs without clearing your input. Paste a Base64 string to decode it back to text, or type any text to get its Base64 representation — results update as you type.
• One-click copy. Copy the full output to your clipboard in one click. The button confirms the action with a brief 'Copied!' label so you know it worked before moving on.
• Client-side privacy. All encoding and decoding runs in your browser using the Web Crypto stack and standard JavaScript APIs. Nothing is sent to a server, logged, or stored. Safe for auth tokens, PII payloads, and internal credentials. As MDN — encodeURIComponent notes, keeping sensitive data local is always preferable to passing it through a remote endpoint.
• Handles common pitfalls. Strips or ignores whitespace and newlines that some encoders insert at 76-character intervals (per MIME), so you can paste wrapped Base64 from email or config files and decode it without manual cleanup.

How to use the Base64 encoder & decoder

Choose the Encode or Decode tab, paste your input, and the result appears immediately. Use the URL-safe toggle when working with JWT or URLs.

1. Select a direction. Click the **Encode** tab to convert text to Base64, or the **Decode** tab to convert Base64 back to text.
2. Paste or type your input. Enter any UTF-8 text (including emoji or CJK characters) to encode, or paste a Base64 string to decode. In a terminal you can generate input with echo -n 'hello' | base64 and paste the result here to verify.
3. Toggle URL-safe mode if needed. Check **URL-safe** when the output will appear in a URL, query parameter, or JWT segment. This replaces + with -, / with _, and removes = padding.
4. Copy the result. Click **Copy** to send the output to your clipboard. In Python you can verify encoded strings with import base64; base64.b64encode(text.encode()) to cross-check results.

Common use cases

• Inspecting JWT tokens. JWT header and payload segments are Base64URL-encoded (standardized in RFC 7519 in 2015). Paste either segment into the Decode tab to read the JSON claims without installing any library. If you also need to generate a random token ID, the [UUID generator](/en/uuid-generator/) handles that.
• Building Basic Auth headers. HTTP Basic Authentication requires the username:password string to be Base64-encoded and sent as Authorization: Basic <token>. Encode your credentials here, then paste the result directly into curl, Postman, or a config file — without sending your password to a third-party service.
• Embedding assets as data URIs. Small images, SVG icons, or custom fonts can be embedded directly in CSS or HTML as data:image/png;base64,<encoded>. Encode your binary content here to generate the Base64 portion, then construct the full data URI in your stylesheet.
• Encoding binary blobs in JSON or YAML configs. Config formats like Kubernetes secrets store binary values (TLS certs, private keys) as Base64 strings because JSON — as defined in RFC 8259 — has no binary type. Use this tool to encode or decode those values when editing manifests by hand.
• Debugging encoded API responses. Some APIs return field values or error details Base64-encoded to preserve binary safety. Decode them here to read the original content, whether that's a protobuf payload, a SAML assertion, or an error message from a service in Boston or London.

Frequently asked questions