How can a startup vet remote vendors or marketplaces before trusting them with core product work?

Ask for concrete case studies in your domain, along with references you can actually talk to. Investigate how they vet their own developers, what their replacement policy is, and how they handle communication, time zones, and escalation. During a trial period, pay attention not just to code quality, but also to transparency about delays and issues. Review contracts for clarity on intellectual property, confidentiality, and termination terms. A good partner will welcome tough questions and be specific in their answers instead of relying on generic promises.