Base64 to ASCII
Converter
Decode any Base64 string back to human readable ASCII text in milliseconds. Runs 100% in your browser your data never leaves your device.
Three Steps to Decoded ASCII
No account, no uploads, no tracking. Just paste and decode.
Paste Base64 String
Copy your Base64 encoded string and paste it directly into the input field, or use the one-click Paste button to pull from your clipboard.
Click Decode
Hit "Decode to ASCII" and the tool instantly converts every Base64 character group back into the original printable ASCII characters.
Copy or Download
Copy the readable text to your clipboard in one click or download it as a .txt file to use in any workflow.
Everything You Need to Decode
Purpose-built for Base64 → ASCII conversion with developer-grade accuracy.
Instant Decoding
Convert Base64 to ASCII with a single click. No delays, no spinners native browser JavaScript delivers results instantly.
URL-Safe Support
Handles both standard Base64 (+ / /) and URL-safe Base64 (- / _) used in JWT tokens, OAuth flows, and URL query parameters.
Character Map View
See exactly how each Base64 character group maps to its ASCII value perfect for debugging encoding issues character by character.
100% Private
All decoding happens locally in your browser. Zero server contact your tokens, credentials, and data never leave your device.
Download Output
Save the decoded ASCII text as a .txt file directly from the tool. No copy paste required for large outputs.
Two-Way Swap
Swap input and output panels with one click to quickly re-encode your ASCII back to Base64 without switching tools.
Base64 → ASCII in Action
Real-world examples you can decode right now. Click any output to copy.
Simple Greeting Text
Base64 → ASCIIHTTP Basic Auth Header
Credentials → ASCIIJWT Payload Decode
URL-Safe Base64 → JSONAPI Key / Secret Token
Base64 → ASCIIWhen to Decode Base64 to ASCII
From API debugging to email troubleshooting Base64 decoding is a daily developer task.
JWT Token Inspection
JSON Web Tokens store header and payload as URL-safe Base64. Decode the payload segment to read user ID, roles, expiry, and claims during API debugging.
HTTP Basic Auth Debugging
The Authorization: Basic … header carries Base64 encoded username:password. Decode it to verify credentials without special tooling.
Email Header Analysis
MIME email headers and subject lines are often Base64-encoded. Decode them to read the original subject, sender name, or attachment metadata.
Environment Variable Secrets
Certificates, keys, and JSON configs are commonly stored as Base64 strings in env vars. Decode them to inspect the raw content before deployment.
OAuth & SSO Tokens
OAuth access tokens and SAML assertions often use Base64 encoding. Decode the payload to inspect scopes, audience, and expiry timestamps.
Reverse Engineering & CTF
Capture the flag challenges and code obfuscation frequently rely on Base64. Quickly decode mystery strings to reveal hidden messages or flags.
The Decoding Process Explained
Base64 encoding represents every 3 bytes of binary data as 4 ASCII characters chosen from a 64-character alphabet (A–Z, a–z, 0–9, +, /). Decoding reverses this: every 4 Base64 characters are converted back to their original 3 bytes.
For text data, those decoded bytes are then interpreted as an ASCII (or UTF-8) string, giving you the readable characters back. The = padding at the end indicates how many bytes of padding were added to reach a 4-character boundary.
URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _, and removes the = padding. Before decoding, these must be swapped back and padding re-added which this tool handles automatically.
Printable ASCII Character Table
Decimal values, hex codes, and characters for ASCII 32–126 the full printable range you'll see in decoded Base64 output.
| Dec | Hex | Char | Dec | Hex | Char | Dec | Hex | Char | Dec | Hex | Char |
|---|
Built for Accuracy & Privacy
Decoding sensitive tokens and credentials deserves a tool you can trust completely.
Your Tokens Stay on Your Device
Decoding JWT tokens, API keys, or auth headers on a remote server creates an unnecessary security risk. This tool runs entirely in your browser no network requests, no logs, no third parties ever see your data.
Decode in Milliseconds, Every Time
No round-trip to a server means no latency. Results appear the instant you click regardless of your internet connection. The tool works fully offline after the initial page load perfect for development on the go.
Character-Level Visibility
The Character Map panel shows exactly how each 4-character Base64 group maps to ASCII values ideal when you're debugging malformed tokens, investigating encoding issues, or simply learning how Base64 works.
Standard and URL-Safe in One Place
No need to reach for a second tool when your token uses URL safe encoding. Switch tabs to handle standard Base64, URL safe Base64 (-/_), and check the character map all in a single interface.
Frequently Asked Questions
Everything you need to know about decoding Base64 to ASCII.
+ and / as the 62nd and 63rd characters, and = for padding. URL-safe Base64 (RFC 4648 §5) replaces + with - and / with _, and typically omits padding, making it safe for use in URLs, filenames, and JWT tokens..): header, payload, and signature. Each segment is URL-safe Base64 encoded. Copy the middle segment (payload) and use the URL-Safe Base64 tab to decode it and read the JSON claims like sub, exp, and iat.=) are added to complete the final group: one = means 1 byte of padding was needed; two == means 2 bytes.atob, TextDecoder). Nothing is transmitted to any server. The tool even works fully offline after the page has loaded safe to use with credentials and private tokens.