# Checkly Checks

> Create and configure Checkly checks including API checks, browser checks, and multi-step checks. Covers check types, assertions, retry strategies, and Playwright integration. Use when creating synthetic monitoring checks, validating APIs, testing web applications, or defining check behavior. Triggers on create check, API check, browser check, Playwright, assertions, monitoring.

- Skill: `modbender/checkly-checks` (Agent Skill)
- Install (CLI): `npx skillmds@latest add modbender/checkly-checks`
- Raw SKILL.md: https://api.skillmd.com/api/skills/modbender/checkly-checks/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: modbender (https://skillmd.com/u/modbender)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/modbender/checkly-checks

---


# checkly checks

Create API checks, browser checks, and multi-step checks.

## Check types overview

| Check Type | Use Case | Technology |
|------------|----------|------------|
| **API Check** | HTTP endpoints, REST APIs | HTTP requests + assertions |
| **Browser Check** | Web applications, user flows | Playwright/Puppeteer |
| **Multi-Step Check** | Complex browser workflows | Playwright (legacy) |
| **Playwright Check Suite** | Full test suites | Playwright projects |

## API Checks

Monitor HTTP endpoints with assertions.

### Basic API check

```typescript
// __checks__/api-status.check.ts
import { ApiCheck, AssertionBuilder } from 'checkly/constructs'

new ApiCheck('api-status-check', {
  name: 'API Status Check',
  request: {
    url: 'https://api.example.com/status',
    method: 'GET',
    assertions: [
      AssertionBuilder.statusCode().equals(200),
      AssertionBuilder.responseTime().lessThan(500),
    ],
  },
})
```

### API check with headers

```typescript
new ApiCheck('authenticated-api-check', {
  name: 'Authenticated API',
  request: {
    url: 'https://api.example.com/user/profile',
    method: 'GET',
    headers: [
      { key: 'Authorization', value: 'Bearer {{API_TOKEN}}' },
      { key: 'Content-Type', value: 'application/json' },
    ],
    assertions: [
      AssertionBuilder.statusCode().equals(200),
      AssertionBuilder.jsonBody('$.user.id').isNotNull(),
      AssertionBuilder.jsonBody('$.user.email').matches(/^.+@.+\..+$/),
    ],
  },
  environmentVariables: [
    { key: 'API_TOKEN', value: process.env.API_TOKEN!, locked: true },
  ],
})
```

### API check with request body

```typescript
new ApiCheck('create-user-api', {
  name: 'Create User API',
  request: {
    url: 'https://api.example.com/users',
    method: 'POST',
    headers: [
      { key: 'Content-Type', value: 'application/json' },
    ],
    body: JSON.stringify({
      name: 'Test User',
      email: 'test@example.com',
    }),
    assertions: [
      AssertionBuilder.statusCode().equals(201),
      AssertionBuilder.jsonBody('$.id').isNotNull(),
      AssertionBuilder.header('Location').matches(/\/users\/\d+/),
    ],
  },
})
```

### Advanced assertions

```typescript
new ApiCheck('advanced-assertions', {
  name: 'Advanced API Assertions',
  request: {
    url: 'https://api.example.com/products',
    method: 'GET',
    assertions: [
      // Status code
      AssertionBuilder.statusCode().equals(200),
      
      // Response time
      AssertionBuilder.responseTime().lessThan(1000),
      
      // Headers
      AssertionBuilder.header('Content-Type').contains('application/json'),
      AssertionBuilder.header('X-RateLimit-Remaining').greaterThan(0),
      
      // JSON body (JSONPath)
      AssertionBuilder.jsonBody('$.products').isArray(),
      AssertionBuilder.jsonBody('$.products.length').greaterThan(0),
      AssertionBuilder.jsonBody('$.products[0].name').isNotNull(),
      AssertionBuilder.jsonBody('$.products[*].price').greaterThan(0),
      
      // Text body
      AssertionBuilder.textBody().contains('success'),
      
      // JSON Schema validation
      AssertionBuilder.jsonBody('$').hasSchema({
        type: 'object',
        properties: {
          products: { type: 'array' },
          total: { type: 'number' },
        },
        required: ['products', 'total'],
      }),
    ],
  },
})
```

### Setup and teardown scripts

```typescript
new ApiCheck('with-setup-teardown', {
  name: 'API with Setup/Teardown',
  setupScript: {
    content: `
      // Setup: Generate auth token
      const response = await fetch('https://api.example.com/auth/token', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          client_id: process.env.CLIENT_ID,
          client_secret: process.env.CLIENT_SECRET,
        }),
      })
      const { access_token } = await response.json()
      process.env.AUTH_TOKEN = access_token
    `,
  },
  request: {
    url: 'https://api.example.com/protected',
    method: 'GET',
    headers: [
      { key: 'Authorization', value: 'Bearer {{AUTH_TOKEN}}' },
    ],
    assertions: [
      AssertionBuilder.statusCode().equals(200),
    ],
  },
  teardownScript: {
    content: `
      // Teardown: Log result
      console.log('Check completed:', response.status)
    `,
  },
})
```

## Browser Checks

Monitor web applications with Playwright.

### Basic browser check

```typescript
// __checks__/homepage.spec.ts
import { test, expect } from '@playwright/test'

test('homepage loads successfully', async ({ page }) => {
  // Navigate
  const response = await page.goto('https://example.com')
  expect(response?.status()).toBeLessThan(400)
  
  // Verify title
  await expect(page).toHaveTitle(/Example Domain/)
  
  // Take screenshot
  await page.screenshot({ path: 'homepage.jpg' })
})
```

### Login flow check

```typescript
// __checks__/login.spec.ts
import { test, expect } from '@playwright/test'

test('user can login', async ({ page }) => {
  // Navigate to login page
  await page.goto('https://app.example.com/login')
  
  // Fill credentials
  await page.fill('input[name="email"]', process.env.TEST_EMAIL!)
  await page.fill('input[name="password"]', process.env.TEST_PASSWORD!)
  
  // Submit form
  await page.click('button[type="submit"]')
  
  // Verify redirect to dashboard
  await expect(page).toHaveURL(/\/dashboard/)
  
  // Verify user is logged in
  await expect(page.locator('.user-name')).toContainText('Test User')
})
```

### E-commerce flow check

```typescript
// __checks__/checkout.spec.ts
import { test, expect } from '@playwright/test'

test('complete purchase flow', async ({ page }) => {
  // Browse products
  await page.goto('https://shop.example.com')
  await page.click('text=Shop Now')
  
  // Add to cart
  await page.click('button[data-testid="add-to-cart"]')
  await expect(page.locator('.cart-count')).toHaveText('1')
  
  // Go to checkout
  await page.click('a[href="/cart"]')
  await page.click('text=Proceed to Checkout')
  
  // Fill shipping info (use test card)
  await page.fill('input[name="cardNumber"]', '4242424242424242')
  await page.fill('input[name="expiry"]', '12/25')
  await page.fill('input[name="cvc"]', '123')
  
  // Complete order
  await page.click('button[type="submit"]')
  
  // Verify success
  await expect(page.locator('.order-confirmation')).toBeVisible()
  await expect(page).toHaveURL(/\/orders\/\d+/)
})
```

### Browser check with construct

```typescript
// __checks__/homepage-browser.check.ts
import { BrowserCheck } from 'checkly/constructs'

new BrowserCheck('homepage-browser-check', {
  name: 'Homepage Browser Check',
  frequency: 5,
  locations: ['us-east-1', 'eu-west-1'],
  code: {
    entrypoint: './homepage.spec.ts',
  },
})
```

## Multi-Step Checks

Complex browser workflows (legacy, prefer Browser Checks).

```typescript
// __checks__/multi-step.check.ts
import { MultiStepCheck } from 'checkly/constructs'

new MultiStepCheck('multi-step-check', {
  name: 'Multi-Step Flow',
  code: {
    entrypoint: './multi-step-script.js',
  },
  runtimeId: '2025.04',
})

// multi-step-script.js
const { chromium } = require('playwright')

async function run() {
  const browser = await chromium.launch()
  const page = await browser.newPage()
  
  await page.goto('https://example.com')
  await page.click('text=Login')
  // ... more steps
  
  await browser.close()
}

run()
```

## Check configuration

### Schedule configuration

```typescript
new ApiCheck('scheduled-check', {
  frequency: 5,  // minutes: 1, 5, 10, 15, 30, 60, 120, 1440
  locations: [
    'us-east-1',
    'us-west-1',
    'eu-west-1',
    'ap-southeast-1',
  ],
  activated: true,  // Schedule check to run
  muted: false,     // Send alerts
})
```

### Tags and organization

```typescript
new ApiCheck('tagged-check', {
  name: 'Tagged Check',
  tags: ['production', 'critical', 'api'],
})
```

### Alert configuration

```typescript
import { EmailAlertChannel } from 'checkly/constructs'

const emailChannel = new EmailAlertChannel('email-alerts', {
  address: 'team@example.com',
})

new ApiCheck('check-with-alerts', {
  name: 'Check with Alerts',
  alertChannels: [emailChannel],
})
```

### Retry strategies

```typescript
import { RetryStrategyBuilder } from 'checkly/constructs'

new ApiCheck('check-with-retries', {
  name: 'Check with Retries',
  retryStrategy: RetryStrategyBuilder.fixedStrategy({
    baseBackoffSeconds: 60,
    maxAttempts: 2,
    maxDurationSeconds: 600,
    sameRegion: true,
  }),
})
```

## Check patterns

### Check groups

```typescript
// __checks__/groups.ts
import { CheckGroup } from 'checkly/constructs'

export const criticalChecks = new CheckGroup('critical-checks', {
  name: 'Critical Checks',
  activated: true,
  muted: false,
  locations: ['us-east-1', 'eu-west-1'],
  frequency: 1,
  tags: ['critical'],
  environmentVariables: [
    { key: 'ENV', value: 'production' },
  ],
})

// __checks__/api.check.ts
import { ApiCheck } from 'checkly/constructs'
import { criticalChecks } from './groups'

new ApiCheck('critical-api', {
  name: 'Critical API',
  group: criticalChecks,  // Inherits group settings
  request: {
    url: 'https://api.example.com/health',
    method: 'GET',
  },
})
```

### Environment-specific checks

```typescript
const environment = process.env.NODE_ENV || 'production'

new ApiCheck(`api-check-${environment}`, {
  name: `API Check (${environment})`,
  request: {
    url: `https://api.${environment}.example.com/status`,
    method: 'GET',
  },
  tags: [environment],
})
```

### Shared helpers

```typescript
// __checks__/helpers.ts
import { AssertionBuilder } from 'checkly/constructs'

export const standardAssertions = [
  AssertionBuilder.statusCode().equals(200),
  AssertionBuilder.responseTime().lessThan(500),
]

// __checks__/api.check.ts
import { ApiCheck } from 'checkly/constructs'
import { standardAssertions } from './helpers'

new ApiCheck('api-check', {
  request: {
    url: 'https://api.example.com/status',
    assertions: standardAssertions,
  },
})
```

## Troubleshooting

### Check fails locally but passes in UI

**Solution**: Test in Checkly runtime (not just Playwright):
```bash
npx checkly test  # Uses Checkly runtime
```

### Environment variables not working

**Solution**:
```typescript
environmentVariables: [
  { key: 'API_KEY', value: process.env.API_KEY!, locked: true },
]
```

### Browser check selector fails

**Solution**: Use more robust selectors:
```typescript
// ❌ Fragile
await page.click('.button')

// ✅ Better
await page.click('button[data-testid="submit"]')
await page.click('text=Submit')
```

## Related Skills

- See `checkly-test` to test checks locally
- See `checkly-deploy` to deploy checks
- See `checkly-playwright` for full test suites
- See `checkly-advanced` for retry strategies