Playwright API mocking is a test-level capability designed to stub network calls within browser-based UI tests.
Specmatic is a contract-driven API contract testing, simulation and validation platform designed to ensure API correctness, realism, and governance across teams, tools, and environments.
Core Philosophy Difference
Aspect
Playwright API Mocking
Specmatic
Design intent
Optimise individual UI tests
Establish APIs as shared, governed contracts
Primary concern
Test isolation and speed
Correctness, realism, and consistency with speed
Scope
Inside Playwright tests
Across the entire delivery lifecycle
What Playwright API Mocking Is Best At
Playwright API mocking excels when teams need:
Fast, localised, ah-hoc stubbing of backend calls
Deterministic UI tests without backend dependencies
Simple simulation of success or failure paths
Tight integration within Playwright-based test suites
It is intentionally lightweight and tester-centric, making it ideal for UI-focused test scenarios.
What Specmatic Is Designed For
While Specmatic can certainly help with mocking backend API calls for designing deterministic UI tests, it also addresses challenges that emerge as systems and organisations scale:
APIs used by multiple consumers (web, mobile, partners)
Parallel development across frontend, backend, and integration teams
Need for realistic mocks that don’t drift from production behaviour
Specmatic uses API specifications as the single source of truth, ensuring all simulations and validations remain aligned with real API expectations.
Key Capability Differences
Dimension
Playwright API Mocking
Specmatic
Source of truth
Test code
API specifications
Schema awareness
None
Full contract enforcement
Mock accuracy over time
Manually maintained
Automatically kept in sync via Specs
Negative & edge cases
Hand-coded
Generated from contracts
Workflow awareness
Stateless
Stateful workflows (Arazzo)
Protocol support
HTTP (browser only)
HTTP, AsyncAPI, GraphQL, SOAP, Proto3
Reusability
Test-specific
Reusable, versioned artefacts
CI & governance
Indirect
First-class quality gates
Why This Difference Matters at Scale
As systems grow, teams often face UI tests passing locally while in staging or production functionality break, inconsistent assumptions between teams, late discovery of breaking changes, and incomplete edge-case testing. Specmatic shifts API correctness earlier in the lifecycle.
Playwright API Mocking vs Specmatic
Dimension
Playwright API Mocking
Specmatic
Primary Purpose
Stub network calls inside Playwright UI tests
Contract-driven API contract testing, simulation, validation, and governance
Low – contract changes automatically reflect in stubs
CI / Pipeline Integration
PARTIAL Indirect (via tests)
YES First-class CI integration with quality gates
Governance & Policy Enforcement
NO Not supported
YES Enforceable API standards and policies
Enterprise Scalability
NO Best for small, test-local use cases
YES Scales across teams, systems, and organisations
Native App Support
Not applicable
Works with Android & iOS native apps and devices
Best Fit Use Case
Fast, localized UI test stubbing
Enterprise-grade API correctness, simulation, and governance
Last updated 20 Dec 2025
When to Choose Which Tool
Use Playwright API Mocking for quick UI stubs and simple API behaviour.
Use Specmatic when APIs are shared, correctness matters, and governance is required.
Summary
Playwright API mocking is a test-level optimisation tool.
Specmatic is a contract-driven platform for API simulation, validation, and governance. It enables fast UI testing without sacrificing API correctness or realism.
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