How to Setup Rest API Monitoring?

REST API monitoring automatically checks whether your API endpoints are reachable, returning correct status codes, and responding with expected data — and alerts you the instant something breaks. This guide shows you exactly how to set up REST API monitoring in MonitoringDaddy in minutes.

What Is REST API Monitoring?

REST API monitoring sends scheduled HTTP requests to your API endpoints from external servers and verifies that each response is healthy. A healthy response typically means the correct HTTP status code (such as 200 OK), an acceptable response time, and — optionally — the presence of a specific keyword or JSON field in the body.

Unlike website uptime monitoring, which focuses on whether an HTML page loads, REST API monitoring is purpose-built for machine-to-machine interfaces: it supports custom HTTP methods (GET, POST, PUT, DELETE), request headers, Bearer token authentication, JSON payloads, and response-body assertions. This makes it the right tool for checking health endpoints, third-party integrations, payment gateways, authentication services, and any other JSON API your application depends on.

Why REST API Monitoring Matters

• APIs fail silently. A broken endpoint rarely triggers a visible error on your front end — users just experience weird behaviour or missing data. Monitoring catches it before they do.
• Third-party dependencies. Your app may call dozens of external APIs. If a payment processor or shipping API goes down, you need to know immediately.
• Deployment regressions. New code can break an endpoint that was working fine. Continuous monitoring catches regressions within minutes of a deploy.
• SLA and uptime reporting. Historical uptime data gives you evidence for SLA compliance and helps engineering teams prioritise reliability work.
• Security token expiry. API keys and Bearer tokens expire. A monitor that checks an authenticated endpoint will alert you when credentials stop working.

How REST API Monitoring Works in MonitoringDaddy

At the chosen interval, MonitoringDaddy sends an HTTP request to your endpoint using the method, headers, and body you configured. It checks the HTTP status code against your expected value, optionally scans the response body for a keyword or JSON string, and records the round-trip response time. If the check fails — wrong status code, missing keyword, timeout, or network error — an alert is dispatched to every channel you configured (email, webhook, Slack, Discord, and more). When the endpoint recovers, a recovery notification follows automatically.

You can also pair API monitoring with keyword monitoring to validate that specific fields appear in JSON responses, providing deeper functional coverage beyond a simple status-code check.

Before You Begin

• Confirm your API URL starts with https:// — plain http:// endpoints are supported but a secure endpoint is strongly recommended.
• Know the correct HTTP method your endpoint expects (GET for read operations, POST for create or action endpoints, etc.).
• Gather any authentication details: Bearer token, API key header, or HTTP Basic credentials.
• Decide what a "healthy" response looks like: expected status code (usually 200) and, optionally, a word or phrase that always appears in a healthy JSON response body.
• Have at least one alert channel ready — an email address or a Slack/Discord/Teams webhook URL.

How to Set Up REST API Monitoring (Step by Step)

Step 1: Monitor Name

Give the monitor a clear, descriptive name so you can identify the endpoint at a glance on your dashboard and in alert emails.

Step 2: API Endpoint URL

Paste the full REST API endpoint you want to monitor, including the path.

If your API exposes a dedicated health or status endpoint, use that — it is lightweight, purpose-built for liveness checks, and avoids side effects. If no health endpoint exists, use a read-only GET endpoint that returns quickly.

Step 3: Monitoring Interval

Choose how frequently MonitoringDaddy polls the endpoint:

• 1 minute — critical production APIs, payment gateways, authentication services
• 5 minutes — most production APIs; a good default
• 15 minutes — non-critical, staging, or low-traffic endpoints

A 5-minute interval means you detect an outage within 5 minutes of it starting at worst, and often faster because checks are distributed across the interval window.

Step 4: HTTP Request Method

Select the HTTP method that matches your endpoint:

• GET — use this for any endpoint that just reads data or checks status. This is correct for most health checks and read-only resources.
• POST — use when the endpoint requires a request body (for example, a /login endpoint or an action API). You can provide a JSON body in the next step.
• PUT / PATCH / DELETE — available for advanced scenarios where you need to verify write operations, though GET and POST cover the vast majority of API monitoring use cases.

Step 5: Request Headers and Authentication

Most production APIs require at least one form of authentication. MonitoringDaddy lets you pass headers with every request.

Bearer Token (most common)

API Key in a custom header

Content-Type for POST requests

You can add multiple headers — click Add Header for each additional name/value pair. Leave headers empty if the endpoint is publicly accessible without authentication.

Step 6: HTTP Authentication (Basic Auth)

If your API uses HTTP Basic Authentication rather than token-based auth, enter the username and password in the dedicated HTTP Authentication fields. Leave both fields empty otherwise — they are entirely optional.

Step 7: Expected Status Code and Response Check

Set the alert condition to URL becomes unavailable. This triggers an alert whenever the endpoint:

• Returns a 5xx server error
• Returns a 4xx client error (such as 401 Unauthorized when a token expires)
• Times out without responding
• Is unreachable due to a DNS or network failure

Optional: JSON keyword / response-contains check

For deeper validation, add a keyword check so the monitor only marks the endpoint as "up" when the response body contains an expected string. This is especially useful for APIs that return 200 OK even when reporting an internal error in the JSON body.

For example, if your health endpoint always returns {"status":"ok","version":"2.1"} when healthy, checking for "status":"ok" ensures you catch cases where the API returns 200 but reports a degraded state in the body. Pair this with dedicated keyword monitoring for even more granular coverage.

Step 8: Alert Channels

Add at least one channel so you are notified the instant a failure is detected and again when the endpoint recovers:

• Email — recommended as a baseline for every monitor
• Webhook — send alerts to Slack, Discord, Microsoft Teams, PagerDuty, or any custom HTTP endpoint

You can add multiple channels per monitor. For critical production APIs, consider both email and a team Slack channel so the right people are alerted immediately, regardless of whether they are checking their inbox.

Step 9: SSL Certificate Monitoring

Decide whether to also monitor the SSL certificate of the API domain:

• ON — receive advance alerts before the certificate expires (recommended for production APIs)
• OFF — monitor API availability only; skip SSL expiry tracking

For a first-time setup, leaving SSL monitoring OFF keeps things simple. You can enable it at any time by editing the monitor.

Step 10: Domain Name Monitoring

Set domain monitoring to OFF unless you also want to track the API domain's registration expiry. For pure REST API uptime and response checks, domain monitoring is not required.

Step 11: Cache Buster

Set the cache buster to enabled. This appends a unique parameter to each request, preventing CDNs, reverse proxies, or API gateways from serving a cached response. Without it, a monitor might report "up" based on a stale cached reply even when the live API is actually down.

Recommended REST API Monitoring Configuration

Advanced Configuration: POST Request with JSON Body

If you need to monitor a POST endpoint — for example, a login API or a data-processing endpoint — switch the method to POST and supply the request body in JSON format. Make sure to include a Content-Type: application/json header.

The response-contains check for "token" confirms the login endpoint is not just returning 200 OK but actually issuing tokens — a meaningful functional test, not just a connectivity check.

Best Practices for REST API Monitoring

• Use a dedicated health endpoint. A lightweight /health or /status route avoids hitting rate limits, triggering side effects, or polluting your analytics.
• Monitor critical paths end-to-end. In addition to the health endpoint, monitor the endpoints your users depend on most — search, checkout, user profile — so you catch partial failures.
• Rotate monitoring credentials separately. Use a dedicated low-privilege API key for monitoring. That way, rotating production keys does not break your monitors, and vice versa.
• Add response-body assertions. A 200 OK from a broken API is worse than a 500 — it masks the problem. Always add a keyword check for a field that only appears in healthy responses.
• Set alert channels for multiple people. Route critical API alerts to a shared Slack channel so the whole team can respond, not just whoever checks email first.
• Complement with server monitoring. API-level monitoring tells you the endpoint is failing; server monitoring tells you why — high CPU, full disk, or memory exhaustion.

Troubleshooting Common Issues

Monitor shows DOWN immediately after setup

Check that the URL is correct and includes https://. Test it in a browser or with curl from your machine. If it loads locally, ensure the endpoint is publicly accessible and not blocked by a firewall or VPN requirement.

401 Unauthorized errors

Your authentication header is missing, malformed, or the token has expired. Double-check the header name (case matters for some APIs) and verify the token is still valid. Consider using a long-lived service account token for monitoring purposes.

Monitor reports UP but the app is broken

Add a response-contains assertion targeting a field that only appears in healthy responses. A /health endpoint returning {"status":"degraded"} with a 200 status code will pass a plain status-code check but fail a keyword check for "status":"ok".

Intermittent timeouts

Occasional timeouts may indicate slow database queries, cold starts (serverless functions), or network congestion. Check your server's response-time history on the MonitoringDaddy dashboard and consider enabling server monitoring to correlate API slowness with resource utilisation.

Next Steps

Once your first REST API monitor is live, expand your coverage with these complementary monitors:

• Add more endpoint monitors for every critical API path your application depends on.
• Enable keyword monitoring for APIs where response-body validation is critical.
• Set up server monitoring to correlate API failures with underlying infrastructure metrics.
• Review pricing plans to find the right check interval and monitor count for your team.

Frequently Asked Questions