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Loader.io
What it is
Loader.io is a cloud-based service for stress-testing web applications and APIs with concurrent connections. You can register a target through its web interface or API, configure a test, then monitor it while it runs. The API supports per-test, per-second, and maintain-load tests. A test can use a URL sequence and settings for duration, client counts, timeouts, error thresholds, scheduled starts, and completion callbacks. Results include counts and summaries for successes, errors, timeouts, and network errors, as well as transferred data, average response time, and average error rate.
A target host must pass automated verification before testing, and each distinct hostname must be verified separately. Tests currently run from Amazon’s US-east datacenter. Integrations include webhooks, CI tools, New Relic, and others. Loader.io has a free plan with 10,000 clients per test, one target host, one-minute tests, and two URLs per test. Pro costs $99.95 per month and includes up to 100,000 clients per test, unlimited target hosts, and unlimited 10-minute tests.
For and against
For
- Supports three API test types.
- Results summarize errors, timing, and transferred data.
- Webhooks can start tests and report completion.
- Integrations include Jenkins, CircleCI, and New Relic.
Against
- Each hostname requires separate verification.
- Free tests are limited to one minute.
- Free plan allows one target host.
- Tests run from the US-east datacenter.
The verdict
Loader.io combines configurable load tests with live monitoring and API-accessible results. Check its host verification requirement and plan limits against the tests you need to run.
Who it suits
Loader.io suits teams that need to exercise web apps or APIs under load and monitor test results. Its free plan may fit tests within its stated client, host, duration, and URL limits.
Plans and prices
Free
10,000 clients / test · 1 target host · 1 min tests · 2 urls per test
Read 4 Oct 2026 · loader.io
Pro
100,000 clients / test · unlimited target hosts · unlimited 10 min tests · 10 urls per test
Read 4 Oct 2026 · loader.io
On the record
- Host limit
- Each unique hostname must be added and verified independently.loader.io · read 4 Oct 2026
- Integrations
- The Help Desk lists webhooks, TravisCI, CircleCI, Jenkins, TeamCity, GitHub Service Hooks, New Relic, and HipChat integrations.support.loader.io · read 4 Oct 2026
- New Relic
- Loader.io can send test results to New Relic Insights in real time and to New Relic, whose dashboard updates at a stated limit of once per minute.support.loader.io · read 4 Oct 2026
- Purpose
- Loader.io is a cloud-based load testing service for stress testing web apps and APIs with thousands of concurrent connections.loader.io · read 4 Oct 2026
- Results
- The results API provides summaries including successes, errors, timeouts, network errors, data transferred, average response time, and average error rate.loader.io · read 4 Oct 2026
- Security
- The maker says load generator IP addresses can change between tests and provides an API endpoint for retrieving the current addresses for allow-listing.loader.io · read 4 Oct 2026
- Support
- The pricing FAQ directs users to [email protected] for questions and says paid plans include priority support.loader.io · read 4 Oct 2026
- Test configuration
- Tests can include a sequence of URLs, a duration, client counts, timeouts, error thresholds, scheduled start times, and completion callbacks.loader.io · read 4 Oct 2026
- Test location
- The pricing FAQ says tests currently run from Amazon’s US-east datacenter.loader.io · read 4 Oct 2026
- Test types
- The API supports per-test, per-second, and maintain-load test types.loader.io · read 4 Oct 2026
- Test workflow
- Users can register a target through the web interface or API, run a test, and monitor it in real time.loader.io · read 4 Oct 2026
- Verification
- Loader.io requires target hosts to pass automated verification before tests, to help prevent using the service to attack sites without their consent.loader.io · read 4 Oct 2026
- Webhook automation
- A test-specific run webhook can trigger a test with a POST request, and a notification webhook can receive a POST when a test completes.support.loader.io · read 4 Oct 2026
