Does HMAC-MD5 upload my file or text to Tool-You servers?

No. HMAC-MD5 runs in this browser tab. Files stay on the device. Limit note: Non-empty key and message. Optional uppercase. Not for passwords.

Should I use HMAC-SHA1 instead of HMAC-MD5?

Use HMAC-MD5 when you need HMAC-MD5 hex and Base64; optional uppercase. Use HMAC-SHA1 when you need HMAC-SHA1 hex and Base64; optional uppercase. They share a category (Crypto) but not the same job.

HMAC-MD5

HMAC-MD5 hex and Base64; optional uppercase.

Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.

What HMAC-MD5 does

Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.

Practical limit for HMAC-MD5: Non-empty key and message. Optional uppercase. Not for passwords. That is why output can differ from heavy desktop Crypto software. Read the tool-specific note again: Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.

How to use HMAC-MD5

Keep this tab on HMAC-MD5 (/crypto/hmac-md5). Pasting into the wrong Crypto tool (for example HMAC-SHA1) changes the job.
Paste or type the input HMAC-MD5 expects. Path hint: crypto · hmac md5. HMAC-MD5 hex and Base64; optional uppercase.
Apply the HMAC-MD5 action only. HMAC-SHA256 is a different transform (HMAC-SHA256 hex and Base64; optional uppercase.). Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.
Copy the output of HMAC-MD5 if you need it elsewhere. Size/complexity still follows: Non-empty key and message. Optional uppercase. Not for passwords.
If the text job is actually HMAC-SHA1 hex and Base64; optional uppercase., leave HMAC-MD5 and open HMAC-SHA1.

When not to use HMAC-MD5

Skip HMAC-MD5 when a neighbor tool matches better — start with HMAC-SHA1 or HMAC-SHA256 — or when the description already warns the job will fail. In the tool’s own words: Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.

Questions about HMAC-MD5

What does HMAC-MD5 do that other Crypto pages on this site do not?: Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords. Short version: HMAC-MD5 hex and Base64; optional uppercase.
Does HMAC-MD5 upload my file or text to Tool-You servers?: No. HMAC-MD5 runs in this browser tab. Files stay on the device. Limit note: Non-empty key and message. Optional uppercase. Not for passwords.
Should I use HMAC-SHA1 instead of HMAC-MD5?: Use HMAC-MD5 when you need HMAC-MD5 hex and Base64; optional uppercase. Use HMAC-SHA1 when you need HMAC-SHA1 hex and Base64; optional uppercase. They share a category (Crypto) but not the same job.
What are the limits of HMAC-MD5?: Non-empty key and message. Optional uppercase. Not for passwords. Also: Keyed MD5 of the message. Optional uppercase hex. Unlike HMAC-SHA256 this is a legacy 16-byte digest. Empty key or message fails. Not for passwords.