Postman mocks the API your spec describes. Gostly mocks the API your service actually serves. APIContext found 75% of production APIs deviate from their published OpenAPI — that gap is the choice.
Postman's mock server is bundled with the dominant API client. If your team already lives in Postman collections, the mock server is a one-click upgrade — examples become endpoints, Faker.js fills in random data, and the spec is the source of truth. For exploratory API testing and design-first workflows, that is genuinely the right ergonomic.
The wedge as of March 2026 is the new free-tier cap: 25 collection runs per month. Past that you are on Basic ($14/seat), Pro ($29/seat), or Enterprise ($49/seat). For any team running mocks in CI on every PR, 25 runs is a single morning.
Gostly comes at mocking from the opposite direction. Instead of generating responses from a spec, it records what the upstream actually returned and replays it. That matters because OpenAPI specs lie often: missing required fields on oneOf / discriminator, Lorem-ipsum payloads where the production API returns denormalised joined data, no signal at all about 429 / partial 5xx behaviour or the specific shape of the GET-after-POST.
| Feature | Postman | Gostly |
|---|---|---|
| Bundled with API client / collection runner | Yes | No |
| Spec-first mocking (OpenAPI / Postman collections) | primary model | import supported |
| Traffic-first mocking (record real upstream) | No | primary model |
| Free-tier collection-run cap | 25 / mo (Mar 2026) | no run cap |
| Stateful flows across requests | examples-driven; limited | roadmap (Q4 2026) |
| Self-hostable | No | single binary or K8s |
| Fixture realism | Faker.js + handlebars in examples | real upstream payloads (PII-scrubbed) |
| AI gap-fill grounded by your traffic | No | Yes |
| Drift detection vs upstream | No | v1 today; canary-replay v2 Q4 2026 |
| Latency / status-code injection | No | Yes |
Roadmap items are explicitly labelled. Stateful flows and drift detection are 2026 roadmap on Gostly's side, not shipping today.
Choose Postman when
Choose Gostly when
| Tier | Postman | Gostly |
|---|---|---|
| Free | 1 user · 25 collection runs / mo (Mar 2026) | Unlimited services · OSS proxy (FSL) · unlimited mock serving |
| Solo / Pro | Basic $14 / seat · Pro $29 / seat | $10 / mo single user · unlimited mocks |
| Team / Enterprise (per-seat) | Enterprise $49 / seat | Team / seat / mo |
| Self-host | SaaS only | $499 / mo Self-host · $25K+ Enterprise |
Hit your Postman 25-runs/mo cap? Gostly Pro is unlimited mocks at $10 / mo (single user); Team is $79 / seat / mo with a 3-seat min. The honest framing: Postman charges for the API client and bundles the mock; Gostly charges for the mock and brings nothing else. If you already pay for Postman, the mock is "free." If you do not, Gostly is the cheaper standalone path.
Bring your existing Postman collection. The Gostly CLI imports the requests, examples, and resolved variables into a flat mock library — pre-request and test scripts are skipped (we don’t evaluate JS), but every saved example is preserved verbatim.
$ gostly import --format postman \
--service-id svc-stripe my-collection.json
✓ Imported 47 mocks from my-collection.json
! request 'create-charge': dropped prerequest script (3 lines) — scripts are not executed on import
! unresolved variables (left literal in URLs/bodies): customerIdImports require an existing service upstream (create one in the dashboard or via gostly services). Resolved Postman variables come from collection variables plus an optional environment overlay; anything we can’t resolve is left literal so you can fix it in the dashboard.
Skip the spec. Record an hour of real upstream traffic and serve that back instead. Unlimited runs from $10 / mo.
Evaluating for a team of 3+? We’d love to talk before you commit.