It is legal to seal a contract without signing it. Because the condition for the establishment of a contract is that the parties need to reach an agreement through consultation, and the parties need to sign or seal the written contract, otherwise the contract will not be established, so it is legal for the contract not to be signed and sealed.

Legal objectivity:

Article 490 of the Civil Code If the parties conclude a contract in the form of a contract, the contract is established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.