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HTTP 401 Unauthorized
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Meaning
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Result appears here as you type
runs in your browser · nothing uploaded
// about this tool

HTTP 401 Unauthorized Online

Updated 2026-10-24

HTTP 401 Unauthorized means the server needs you to authenticate, and either you haven't, or the credentials you sent aren't valid; despite the name, it's about missing or bad login/auth, not about permissions. It's the code you'll see from an API when a token is missing, expired, or malformed.

The fix is almost always in how credentials are being sent: check for an expired token, a missing Bearer prefix on the Authorization header, or a token issued for the wrong environment. If you're authenticated but still blocked, that's 403 Forbidden instead, a different problem entirely. For every other status code at once, use the full HTTP Status Codes reference.

// how to use

  1. 1 The code is already looked up below, with 401 pre-filled.
  2. 2 Type any other status code to look that one up instead.
  3. 3 Copy the result, or use the full HTTP Status Codes reference for every code at once.

// examples

The code itself
Input
401
Output
401 Unauthorized: Client Error (4xx). Authentication is required and has failed or not been provided.
The code it's often confused with
Input
403
Output
403 Forbidden: you're authenticated, but not allowed to access this resource.

// common uses

Debugging why an API call with a token still fails authentication Distinguishing a login problem (401) from a permissions problem (403) Explaining a 401 in an API integration guide Checking what a status code in server logs actually means

// faq

Is anything uploaded to a server?
No. The match happens against a table already in your browser, so nothing you type is sent anywhere. Despite its name, 401 is really about authentication failing, not authorization; "Unauthenticated" would have been the more accurate name.
What's the difference between 401 and 403?
401 means the server doesn't know who you are (no credentials, or invalid ones). 403 means it DOES know who you are, but you're not allowed to do this. 401 is a login problem; 403 is a permissions problem.
Why does 401 sometimes come with a WWW-Authenticate header?
The HTTP spec requires a 401 response to include a WWW-Authenticate header describing how to authenticate, which is why some 401s trigger a browser's built-in login popup, and API clients read it to know which auth scheme (Bearer, Basic) is expected.
My API token looks correct. Why am I still getting 401?
Common causes are an expired token, a missing "Bearer " prefix in the Authorization header, clock skew invalidating a time-based token, or sending the token to the wrong environment (staging vs production).
Does 401 mean my account doesn't exist?
Not necessarily; it just means the credentials sent with THIS request weren't valid. The account could exist and be fine; the token, password, or session just didn't authenticate.

// works with your data

HTTP 403 Forbidden HTTP 404 Not Found HTTP 429 Too Many Requests HTTP Status Codes JWT Decoder Meta Tag Generator

Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/http-401 \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"401"}'