# Mock Service Worker (MSW)

- **Canonical URI:** https://www.vioscale.ai/software/mock-service-worker-msw
- **Category:** API Mocking
- **Homepage:** https://mswjs.io
- **Also known as:** mock-service-worker-msw
- **Profile claimed by vendor:** no
- **Last updated:** 2026-08-26T19:17:26.856Z

## Vioscale score

**58.1 / 100**, confidence 81% (high). Computed 2026-09-01.

Composite of weighted, independently-sourced signals (no user reviews, no vendor payment).

| Signal | Score | Weight | Contribution | Evidence present |
|---|--:|--:|--:|:--:|
| price_level | 100 | 0.052 | 5.2 | ✓ |
| reliability | 0 | 0.073 | 0 | - |
| capabilities | 0 | 0.084 | 0 | - |
| repo_stars | 80.3 | 0.026 | 2.1 | ✓ |
| integrations | 27.4 | 0.09355555555555557 | 2.6 | ✓ |
| dependent_projects | 67.9 | 0.063 | 4.3 | ✓ |
| dev_activity | 0 | 0.094 | 0 | - |
| release_cadence | 98.9 | 0.052 | 5.1 | ✓ |
| security_posture | 0 | 0.073 | 0 | - |
| package_downloads | 0 | 0.136 | 0 | - |
| security_score | 62 | 0.042 | 2.6 | ✓ |
| pricing_transparency | 25 | 0.084 | 2.1 | ✓ |
| community_qa_activity | 0 | 0.063 | 0 | - |

## Pricing

_As of 2026-08-17, [verify at source](https://mswjs.io). Independently observed._

Open source · Free tier

## About

An API mocking library that intercepts network requests at the browser and Node.js levels, allowing consistent mock responses across testing frameworks, tools, and applications without requiring client-specific stubs or configuration.

_Independently observed._

## Platform & deployment

- **Platforms:** CLI, Web

## Integrations (8)

_Independently observed._

- Vitest
- Playwright
- Storybook
- React Native
- Express
- fetch
- axios
- react-query

## Release history

| Version | Date | Type |
|---|---|---|
| [v2.15.0](https://github.com/mswjs/msw/releases/tag/v2.15.0) | 2026-07-08 | stable |
| [v2.14.7](https://github.com/mswjs/msw/releases/tag/v2.14.7) | 2026-07-07 | stable |
| [v2.14.6](https://github.com/mswjs/msw/releases/tag/v2.14.6) | 2026-05-11 | stable |
| [v2.14.5](https://github.com/mswjs/msw/releases/tag/v2.14.5) | 2026-05-08 | stable |
| [v2.14.4](https://github.com/mswjs/msw/releases/tag/v2.14.4) | 2026-05-07 | stable |
| [v2.14.3](https://github.com/mswjs/msw/releases/tag/v2.14.3) | 2026-05-04 | stable |
| [v2.14.2](https://github.com/mswjs/msw/releases/tag/v2.14.2) | 2026-04-29 | stable |
| [v2.14.1](https://github.com/mswjs/msw/releases/tag/v2.14.1) | 2026-04-29 | stable |
| [v2.14.0](https://github.com/mswjs/msw/releases/tag/v2.14.0) | 2026-04-29 | stable |
| [v2.13.6](https://github.com/mswjs/msw/releases/tag/v2.13.6) | 2026-04-24 | stable |
| [v2.13.5](https://github.com/mswjs/msw/releases/tag/v2.13.5) | 2026-04-23 | stable |
| [v2.13.4](https://github.com/mswjs/msw/releases/tag/v2.13.4) | 2026-04-16 | stable |
| [v2.13.3](https://github.com/mswjs/msw/releases/tag/v2.13.3) | 2026-04-14 | stable |
| [v2.13.2](https://github.com/mswjs/msw/releases/tag/v2.13.2) | 2026-04-08 | stable |
| [v2.13.1](https://github.com/mswjs/msw/releases/tag/v2.13.1) | 2026-04-07 | stable |

_… and 5 earlier release(s)._

## Security & compliance


Known vulnerabilities: 0 (0 in the last 12 months) ([source](https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=npm&package_name=msw&per_page=100)). A count reflects scale and disclosure, not quality.

## Facts

Every value below carries its source and our confidence. Facts are re-crawled on a freshness schedule.

### integrations

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| integrations.count | 8 | [link](https://mswjs.io) | 2026-08-17 | 60% (medium) |

### market

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| market.availability | `{"primaryMarkets":[],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` | [link](https://mswjs.io) | 2026-08-17 | 75% (high) |

### pricing

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| pricing.free_tier | yes | [link](https://mswjs.io) | 2026-08-17 | 60% (medium) |
| pricing.price_level | free | [link](https://mswjs.io) | 2026-08-17 | 60% (medium) |
| pricing.model | commercial | [link](https://mswjs.io) | 2026-08-26 | 40% (low) |

### adoption

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| adoption.github_stars | 18,168 | [link](https://github.com/mswjs/msw) | 2026-08-26 | 90% (high) |
| adoption.dependent_repos | 11,851 | [link](https://packages.ecosyste.ms/api/v1/packages/lookup?repository_url=https%3A%2F%2Fgithub.com%2Fmswjs%2Fmsw) | 2026-08-26 | 85% (high) |

### language

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| language.primary | TypeScript | [link](https://github.com/mswjs/msw) | 2026-08-26 | 90% (high) |

### license

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| license.spdx | MIT | [link](https://github.com/mswjs/msw) | 2026-08-26 | 95% (high) |

### release

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| release.cadence_days | 2 | [link](https://github.com/mswjs/msw/releases) | 2026-08-26 | 70% (medium) |

### security

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| security.scorecard | 6.2 | [link](https://api.securityscorecards.dev/projects/github.com/mswjs/msw) | 2026-08-26 | 90% (high) |
| security.vulnerabilities | `{"count":0,"source":"https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=npm&package_name=msw&per_page=100","last_12m":0,"max_severity":null}` | [link](https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=npm&package_name=msw&per_page=100) | 2026-08-26 | 90% (high) |

---
*Source: Vioscale (https://www.vioscale.ai/software/mock-service-worker-msw). Independent, evidence-based software intelligence. Cite the canonical URI.*