If you owe money without an iou, only the chat record can be used as evidence, but the party who takes the chat record as evidence should also provide authentication materials issued by authoritative departments such as notarial certificate to prove the integrity of the chat record and that the other party is indeed the person involved, otherwise it will be difficult for the court to judge the case through a single chat record.

Is there no debt to sue?

You can sue without an iou. The parties can provide transfer records and SMS chat records to prove that they did provide loans to the other party, or that they had witness certificates, or that the other party directly approved the loans. Even if there is no IOU, the fact of borrowing can be recognized.

Legal basis: Article 676 of the Civil Code of People's Republic of China (PRC).

If the borrower fails to repay the loan within the agreed time limit, it shall pay overdue interest in accordance with the agreement or relevant state regulations.

Chapter six hundred and eighty

It is forbidden to lend at high interest, and the interest rate of borrowing shall not violate the relevant provisions of the state. If there is no agreement on the payment of interest in the loan contract, it shall be deemed that there is no interest. If the loan contract does not specify the method of interest payment, and the parties cannot reach a supplementary agreement, the interest shall be determined according to the local or the parties' trading methods, trading habits, market interest rates and other factors; Loans between natural persons are regarded as having no interest.