Validate ASCII
Check whether text contains only 7-bit ASCII characters. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Validate ASCII
- 1. Paste the text to check. Drop the string into the input pane: a config value, an email subject, a source file snippet. The check runs against every character, not just the ones you can see.
- 2. Interpret the verdict. If every character falls in the 7-bit range 0-127 the tool reports Valid ASCII. Otherwise it flags the input, catching smart quotes, accented letters, emoji and invisible Unicode spaces that all look harmless on screen.
- 3. Copy or act on the result. Copy the verdict for a ticket, or fix the flagged characters in your source and re-check. Iterating until the input validates takes seconds because the result updates as you edit.
When to use Validate ASCII
Validate ASCII tells you definitively whether a string is pure 7-bit ASCII. Plenty of systems still require it: SMTP headers, some legacy APIs, identifier rules in older toolchains. The failures they produce rarely mention encoding, so being able to prove or rule out a stray non-ASCII character saves real debugging time.
- Hunting the character that broke a build. A YAML file or shell script fails with a cryptic syntax error after someone pasted from a Word doc. Validate the suspicious lines to confirm a curly quote or non-breaking space is the culprit.
- Pre-flighting data for a legacy system. An EDI feed or AS/400 integration rejects anything outside 7-bit ASCII. Check exported field values before transmission instead of discovering the failure in the partner's error report.
- Enforcing ASCII-only identifiers. Package names, env var keys and DNS hostnames commonly disallow Unicode. Validate a proposed name up front so the registry or resolver never gets the chance to reject it.
- Auditing copy-pasted credentials. An API key pasted from a chat app mysteriously fails authentication. Validating it reveals whether an invisible zero-width character or smart punctuation hitched a ride during the copy.
Examples
Valid
Input
Hello
Output
Valid ASCII
About the Validate ASCII tool
Validate ASCII does its work locally, right in the browser. Check whether text contains only 7-bit ASCII characters. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the ASCII Tools collection on EditSafely, a set of 81 small, focused ASCII utilities that share the same instant, private workspace.
There is nothing to configure. Provide the input and the result appears on its own. A worked example further down the page shows exactly what the tool produces for a real input.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Is Validate ASCII free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.