Good Seal
Notes

19 August 2026 · 2 min read

The six things a contract actually needs

A contract is not defined by having a signature line at the bottom. It is defined by six things being true, and a document can fail every one of them while still looking exactly like a contract.

A signature makes a document look official. It does not, on its own, make it a contract. Contract law asks six separate questions, and a document can have a beautifully formatted signature block and still fail all six of them.

1. Offer

One party has to propose specific terms clearly enough that the other side can simply say yes to them - a price, a scope, a deadline. "Let's work something out sometime" is not an offer; a rate, a scope of work, and a start date is.

2. Acceptance

The other party has to agree to those same terms, without changing them. Agreeing to different terms is not acceptance - it is a counter-offer, and the original offer is now off the table.

3. Consideration

Something of value has to move both ways. Money for services is the obvious case, but consideration can be a promise, access, or anything else with value - what it cannot be is nothing. A one-sided promise, with nothing given in return, is usually not an enforceable contract at all.

4. Capacity

Both parties have to be legally able to enter into the agreement - old enough, mentally competent, and, for a company, actually authorised to sign on its behalf. A contract signed by someone without the authority to bind their employer can be challenged on capacity alone, however clean the rest of the document is.

5. Mutual intent

Both sides have to have intended to create a legally binding relationship, not a casual understanding between friends. This is why a text message saying "sure, I'll do it for 500" can be a contract in a business context and nothing at all between two people splitting a dinner bill.

6. Legality

The subject of the contract has to be legal. A contract to do something illegal is not enforceable no matter how carefully the rest is written - courts will not step in to enforce an agreement to break the law.

What this means for the document itself

A signature does not create any of these six things. It is evidence that a specific person agreed to whatever terms the document already contains. This is why a contract signed by someone with no authority to sign it, or offering nothing in return, can be unenforceable even with a cryptographic signature and a complete audit trail attached to it.

A signing platform can prove who signed and when, to a very high standard. It cannot verify capacity or legality for you - that is a different job, done before the document is ever uploaded, not after.

Good Seal is a free DocuSign alternative: upload a PDF, place the fields, email a link. The other side signs in the browser and everyone gets a sealed copy.

Send a document, free

KEEP READING

What actually makes a document legally bindingNot the signature itself, and not the font size of the fine print. Here is what a court is actually checking for once a contract already exists.Does an electronic signature work outside your own country?Sending a contract abroad does not usually change whether the signature holds up - but there are real exceptions worth knowing before assuming it is fine.Do you need a signing platform, or just a PDF and an email?Sometimes the honest answer is no. Here is how to tell which situation you are actually in.What is actually in a sealed PDFA walk through the finished file: the stamped fields, the certificate page, the detached PKCS#7 signature, and how to verify it yourself with openssl.Addendum or amendment: what's the differenceBoth change a contract after it has been signed. They are not interchangeable, and using the wrong one can create a document that contradicts itself.15 kinds of contracts you'll actually run intoMost lists like this cover the contracts a law firm handles. Here are the ones an actual freelancer or small business sends.What to put in a freelance contractThe clauses that actually prevent a dispute later, not a wall of boilerplate nobody reads.Are electronic signatures admissible in court?Yes - and they usually hold up better than paper. But admissibility depends on the evidence behind the signature, not the signature itself.Radio button or checkbox: how to pick the right fieldOne is for choosing exactly one option. The other is for anything else. Getting it backwards on a contract quietly creates a document that can be filled in two contradictory ways.What DocuSign actually costs, and why we stopped paying itWe worked out what it costs to send one document for signature. It is a fraction of a cent. Here is what we were paying instead.Digital signature vs electronic signature: what's actually differentThe two terms get used as if they mean the same thing. They don't, and the gap between them is where a lot of vendors make their money.Is an electronic signature legally binding?Short answer: almost always, and it has been for twenty years. The longer answer is about evidence, not about the signature itself.