Agents need deterministic facts that a model cannot supply on its own: a ZIP code, an IP location, a coordinate, a sanctions match, a permit record or a weather observation.
The best agent APIs share four traits:
- Deterministic: the same input returns the same shape.
- Low cost per call: usually $0.001-$0.02.
- High volume: one agent task can trigger dozens of calls.
- Hard to fake: the data comes from a real source, not a prompt.
The shortlist
| Category | Why agents pay | Demand | Moat | Difficulty |
|---|---|---|---|---|
| ZIP / address validation | Every address workflow needs it | Very high | Medium: coverage and speed win | Medium |
| Sanctions / PEP screening | AML first pass before onboarding | High | High: list freshness and explainability | High |
| IBAN / BIC validation | Validate bank details before payout | High | Low-medium | Low |
| SEC EDGAR / filings | Equity research and due diligence | Medium | Medium | Low |
| Weather / geocoding | Travel, delivery, insurance | Medium | Low | Low |
| Email / phone verification | Clean signups and outreach | High | Low | Low |
| Building permits / public records | Property, insurance, contractor leads | Medium | High: local coverage is painful | High |
| Screenshot / PDF capture | Visual evidence for vision agents | Medium | Low | Low |
| Crypto market data | Treasury, payments, trading agents | Medium | Low-medium | Low |
| Web search / scraping | Research agents | Very high | Low: crowded | Medium |
Where to start
Best initial focus: address/ZIP intelligence, IP intelligence, geocoding, weather and sanctions screening.
They are essential, have clear buyers, and can be priced per call without a sales-led motion. ZIP codes are crowded, but the market is enormous and agents care about coverage, latency and a stable schema more than brand. A niche country or a specific vertical (property, logistics, recruitment) can still win.
Best long-term moat: public records. Permits, licenses, property and local-government data are fragmented, messy and expensive to normalize. That pain is the moat. It is also the slowest to build.
Least attractive first choice: another general web-search API. It is crowded, the upstream costs are real, and the differentiation is mostly marketing.
Pricing notes
- Charge per call, not per token or per seat.
- Start at $0.001-$0.005 for commodity data.
- Charge $0.01-$0.05 for compliance or public-record evidence.
- Offer a free sample route so an agent can test the shape before paying.
- Settle after a successful response.
- Publish a receipt and a reliability score.
What agents actually check
Before paying, a well-built agent checks:
- the price is below its cap;
- the network and asset are supported;
- the
payTowallet is the one on the listing; - the route returns the shape it expects;
- the API has a recent verified call;
- the response is not a second 402 or an HTML error page.
If your API makes those six checks easy, you will get more repeat calls than a prettier alternative.
The practical conclusion
The money in agent APIs is not in “AI”. It is in data plumbing with a payment rail. Pick a fact that agents need, make it reliable, price it in cents, and publish proof that it works.