LocalStack vs Prism

From $39 per licence/month (Base, billed annually; $45 monthly)

Free and open source

Plans are Hobby (free, non-commercial), Base $39 and Ultimate $89 per licence/month billed annually, then Enterprise. Commercial use needs a paid licence, and the higher tiers are what unlock advanced IAM enforcement and the wider service coverage.

Free and open source. You pay in engineering time and CI minutes.

Hobby tier is free but explicitly non-commercial, and LocalStack has said the Community emulator will no longer receive product updates.

Everything, self-hosted

Category standard

LocalStack · since 2017

Established

Stoplight (SmartBear) · since 2017

• Integration tests against AWS services run offline in seconds at no cloud cost.
• Removes the shared-sandbox-account contention that plagues cloud teams.
• Works with Terraform and CDK, so infrastructure code is testable.

• The mock is generated from the spec, so it cannot silently diverge from the contract.
• Validation proxy mode checks that a real implementation matches its own spec.
• Zero configuration beyond having an OpenAPI file.

• No longer open source: the Community edition is end-of-life, the repo is archived, and running it now requires an account and auth token.
• Using it in CI counts as commercial use, so the free tier does not cover the case most teams want it for.
• Emulation is not identical to AWS; some behaviours and IAM semantics differ.

• Useless without an accurate OpenAPI document.
• Limited stateful behaviour — it is spec-driven, not scenario-driven.
• Generated example data is uninteresting unless examples are in the spec.

AWS-native teams whose tests currently depend on a shared cloud account, and who are willing to pay for a licence now that the free community route has closed.

Design-first API teams who want mocks that are provably in sync with the contract.