Gostly vs the alternatives
Every comparison here admits where the other tool wins. Gostly’s wedge is the same one each time: it records your real upstream traffic and replays it byte-for-byte, self-hosted, with no LLM in the request path.
API mocking
Gostly vs Beeceptor
Beeceptor is a hosted, rule-authored mock service. Gostly is self-hosted and records real traffic — replayed byte-for-byte inside your perimeter. Where each one wins.
Gostly vs Hoverfly
How Gostly differs from Hoverfly: learning from real traffic, structural redaction, AI-only-at-the-edge match cascade.
Gostly vs Microcks
How Gostly differs from Microcks: contract-light, traffic-derived, structural security model.
Gostly vs Mockoon
How Gostly differs from Mockoon: real-traffic learning vs hand-built mocks, with tenant-aware persistence.
Gostly vs Optic
How Gostly differs from Optic: serving replay traffic to a running application vs documenting API drift.
Gostly vs Postman
How Gostly differs from Postman Mock Servers: in-process replay, tenant isolation, no manual mock authoring.
Gostly vs Prism
Prism mocks your OpenAPI spec. Gostly records your real upstream and replays it byte-for-byte. Polymorphism, drift, and stateful flows where Prism falls short.
Gostly vs WireMock
How Gostly differs from WireMock: traffic-derived libraries, structural redaction, and an AI-at-the-edge match cascade rather than hand-written stub mappings.
Agent runtime & observability
Gostly vs Microsoft AGT
How Gostly differs from Microsoft Agent Governance Toolkit: AGT enforces policy at the agent boundary; Gostly proves behavior matches contract via deterministic upstream replay and signed audit trail.
Gostly vs AWS AgentCore
How Gostly differs from AWS AgentCore Policy: Gostly is transport-agnostic and multi-cloud, with byte-equivalent upstream simulation rather than Bedrock-bundled policy gating.
Gostly vs Datadog LLM Experiments
How Gostly differs from Datadog LLM Experiments: deterministic pre-deploy regression signal at the agent-to-API boundary, complementary to Datadog's post-deploy observability.
See it on your own traffic
Point Gostly at a staging upstream for an hour and judge the mock it produces. Free, self-hosted, no SDK or code change.