How can I obtain my employment records for free?

You don't. You call your old employers... and pay them what they ask to reproduce and mail them to you. Postage isn't free.

What records are you looking for? There is no place I know of, other than the SSA, that keeps a complete record of a US citizen's employment record. And the SSA won't give out that info.

If you explain why you ask and what you are looking for we may be able to help further.