Base64 Viewer
Encode text or files to Base64, decode Base64 strings, and preview images — all in the browser.
What is Base64 Viewer?
A Base64 Viewer decodes Base64-encoded strings and displays their content in a human-readable or usable format. Base64 is an encoding scheme that converts binary data — such as images, files, or arbitrary bytes — into a string of ASCII text characters. This makes binary data safe for transmission through text-based protocols like HTTP, JSON, XML, and email, which were not designed to handle raw binary. However, Base64 strings are completely unreadable as-is, making a decoder essential for working with encoded data.
Base64 appears constantly in web development: images embedded directly in HTML or CSS as data URLs (data:image/png;base64,...), JWT (JSON Web Token) payloads, Basic Authentication credentials in HTTP headers, email attachments in MIME format, API responses containing binary data, and cryptographic keys in PEM format. Each of these requires decoding to understand or use the underlying data.
Web developers debugging authentication flows, security researchers analyzing JWTs and encoded payloads, email system administrators troubleshooting MIME attachments, data engineers decoding API responses, and anyone who encounters a Base64 string and needs to understand what it represents uses a Base64 viewer. The tool handles both decoding (Base64 to original content) and encoding (any text or data to Base64), and often detects whether the decoded content is an image, text, JSON, or other recognizable format to display it appropriately.
How to Use Base64 Viewer
- 1Step 1: Paste your Base64-encoded string into the input field — include or exclude the data URL prefix (data:image/png;base64,) as the tool typically handles both formats.
- 2Step 2: Click Decode to convert the Base64 string back to its original form — the tool attempts to detect whether the output is text, JSON, an image, or binary data.
- 3Step 3: If the decoded content is an image, the viewer renders it visually alongside the decoded data so you can see exactly what image was embedded in the Base64 string.
- 4Step 4: If the decoded content is text or JSON, the viewer displays it formatted and readable — you can then copy the plain text or further process the JSON data.
- 5Step 5: To encode content to Base64, paste your text or upload a file into the encode input and copy the resulting Base64 string for use in your code, configuration, or API call.
Benefits of Using Base64 Viewer
- ✓Decode Any Base64 String: Convert unreadable Base64 text back to its original content instantly — whether that is an image, plain text, JSON payload, or any other encoded data.
- ✓Debug JWT Tokens: Decode the header and payload sections of JWT tokens to inspect claims, expiry times, user identifiers, and other authentication data during development.
- ✓Preview Embedded Images: Render the actual image from a Base64 data URL to verify it is the correct image before embedding it in HTML, CSS, or sending it in an API response.
- ✓Inspect API Payloads: Decode Base64-encoded fields in API responses to understand what data your application is receiving, essential for debugging integrations with external services.
- ✓Test Data URL Generation: Encode small images to Base64 data URLs for CSS backgrounds or HTML img tags to eliminate HTTP requests for tiny UI elements.
- ✓Verify Authentication Headers: Decode Basic Auth headers (encoded as Base64) to confirm credentials are being transmitted correctly during API authentication troubleshooting.
Example
About Base64 Viewer
Base64 Viewer encodes text or files to Base64 and decodes Base64 strings back to their original form. For image Base64 data URLs, it renders a live preview of the image. Useful for developers working with embedded media and data URI schemes.
- Text and file Base64 encoding
- Decodes Base64 to text or file
- Live image preview from data URL
- Copy encoded or decoded output