# What is Proof of concept (PoC)?

> A proof of concept (PoC) is a time-boxed trial run before purchase, in which a buyer tests whether a product actually works against its own data, systems and users. Unlike a demo, which the vendor controls, a PoC is designed to answer specific questions the buyer wrote down in advance.

Last updated: 2026-07-27

The failure mode of a PoC is not technical, it is definitional. A PoC without written success criteria becomes an extended demo: everyone is impressed, nobody can say whether it passed, and the decision reverts to whoever advocated loudest.

A well-formed PoC states, before it starts: the questions being tested, the data it will run against, who will use it, how long it runs, and what result constitutes a pass. If a question cannot be answered by running the software — pricing at scale, roadmap commitments, support responsiveness — it does not belong in the PoC; it belongs in the contract.

PoCs are expensive on both sides. The buyer commits internal engineering and user time; the vendor commits solution-engineering hours that are lost if the deal does not close. That cost is why PoCs should come late, after cheaper filters have already removed unsuitable vendors — which is exactly what structured information exchange does earlier in the process. A PoC is the right tool for questions only real usage can answer, and the wrong tool for questions a documented answer would have settled in an hour.

In Japanese enterprises the PoC often also serves an internal function: producing evidence for the 稟議 that authorises the purchase. Knowing that in advance changes what should be measured, because the audience is not only the evaluating team.

## Related terms

- [Vendor evaluation](https://agent-door.com/glossary/vendor-evaluation)
- [Ringi (稟議)](https://agent-door.com/glossary/ringi)
- [RFI, RFP and RFQ](https://agent-door.com/glossary/rfi-rfp-rfq)
- [Total cost of ownership (TCO)](https://agent-door.com/glossary/total-cost-of-ownership)

## Frequently asked questions

### How long should a PoC run?

Long enough to observe real usage patterns, short enough that the team does not drift — commonly two to six weeks. The right length follows from the questions being tested; if you cannot say what a longer PoC would reveal, it is not longer, it is just later.

### Should a PoC be paid?

A paid PoC signals genuine intent and usually secures better vendor resourcing. Free PoCs are common for standard SaaS but tend to receive best-effort support, which can produce a result that reflects vendor attention rather than product fit.

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