Does HMAC-SHA1 upload my file or text to Tool-You servers?

No. HMAC-SHA1 runs in this browser tab. Files stay on the device. Limit note: Non-empty key and message. Optional uppercase hex.

Should I use HMAC-SHA256 instead of HMAC-SHA1?

Use HMAC-SHA1 when you need HMAC-SHA1 hex and Base64; optional uppercase. Use HMAC-SHA256 when you need HMAC-SHA256 hex and Base64; optional uppercase. They share a category (Crypto) but not the same job.

HMAC-SHA1

HMAC-SHA1 hex and Base64; optional uppercase.

Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.

What HMAC-SHA1 does

Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.

This URL is only for HMAC-SHA1 (crypto · hmac sha1). HMAC-SHA1 hex and Base64; optional uppercase. Other Crypto tools on Tool-You look similar in the chrome, so the job definition below is the part that belongs to HMAC-SHA1 alone: Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.

How to use HMAC-SHA1

Keep this tab on HMAC-SHA1 (/crypto/hmac-sha1). Pasting into the wrong Crypto tool (for example HMAC-SHA256) changes the job.
Paste or type the input HMAC-SHA1 expects. Path hint: crypto · hmac sha1. HMAC-SHA1 hex and Base64; optional uppercase.
Apply the HMAC-SHA1 action only. Hash Text is a different transform (Hash text with SHA-2, SHA-1, or MD5.). Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.
Copy the output of HMAC-SHA1 if you need it elsewhere. Size/complexity still follows: Non-empty key and message. Optional uppercase hex.
If the text job is actually HMAC-SHA256 hex and Base64; optional uppercase., leave HMAC-SHA1 and open HMAC-SHA256.

When not to use HMAC-SHA1

Skip HMAC-SHA1 when a neighbor tool matches better — start with HMAC-SHA256 or Hash Text — or when the description already warns the job will fail. In the tool’s own words: Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.

Questions about HMAC-SHA1

What does HMAC-SHA1 do that other Crypto pages on this site do not?: Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only. Short version: HMAC-SHA1 hex and Base64; optional uppercase.
Does HMAC-SHA1 upload my file or text to Tool-You servers?: No. HMAC-SHA1 runs in this browser tab. Files stay on the device. Limit note: Non-empty key and message. Optional uppercase hex.
Should I use HMAC-SHA256 instead of HMAC-SHA1?: Use HMAC-SHA1 when you need HMAC-SHA1 hex and Base64; optional uppercase. Use HMAC-SHA256 when you need HMAC-SHA256 hex and Base64; optional uppercase. They share a category (Crypto) but not the same job.
What are the limits of HMAC-SHA1?: Non-empty key and message. Optional uppercase hex. Also: Keyed SHA-1 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a 20-byte digest. Empty key or message fails. Local only.