Test Agents
When Calibre synthetic monitoring analyses your Site, it uses a Test Agent. Test Agents run Google Lighthouse with a recent Google Chrome browser version. Changes made to Test Agents are published on our Changelog.
You can customise selected Test Agent settings, such as location, test schedule, custom headers, cookies, and authentication.
Test locations
The Test location option lets you choose one out of 17 global locations, where the Site will be tested from. With multiple available locations, you can ensure the performance of the site is equally good no matter where your audience is.
Test Agent IP addresses Recently updated
By default, Test Agents use dynamic IP addresses. When using dynamic IP addresses, the IP address of the Test Agent will change between each test. In contrast, fixed IP addresses are the same for each test.
Fixed IPV4 addresses are helpful to allow-list Agent web traffic through firewalls, CDNs, analytics and other security mechanisms.
You can switch between dynamic and fixed IP addresses on a per Site basis. To switch to fixed addresses, visit Site → Synthetic → Settings → Agent IP Address, then select Fixed IP Address and press Save.
Once you switch to fixed IP addresses, the corresponding test location IP address will be displayed. Alternatively, you can view all Agent IP addresses below.
View Agent IP addresses
| Location | API LocationTag | IP Address |
|---|---|---|
| 🇸🇬 Singapore | Singapore | 13.229.179.153 |
| 🇮🇳 Mumbai, India | Mumbai | 52.66.138.107 |
| 🇯🇵 Tokyo, Japan | Tokyo | 13.115.202.63 |
| 🇧🇷 São Paulo, Brazil | SaoPaulo | 52.67.68.61 |
| 🇰🇷 Seoul, Korea | Seoul | 13.125.97.18 |
| 🇺🇸 Ohio, USA | Ohio | 18.218.2.213 |
| 🇺🇸 Oregon, USA | Oregon | 34.215.172.173 |
| 🇮🇪 Ireland | Ireland | 52.212.252.70 |
| 🇦🇺 Sydney, Australia | Sydney | 54.79.69.167 |
| 🇺🇸 Northern California, USA | California | 54.177.66.94 |
| 🇩🇪 Frankfurt, Germany | Frankfurt | 35.156.32.45 |
| 🇺🇸 North Virginia, USA | NorthVirginia | 52.206.10.99 |
| 🇨🇦 Central Canada | Canada | 35.182.148.199 |
| 🇬🇧 London, United Kingdom | London | 35.176.185.182 |
| 🇸🇪 Stockholm, Sweden | Stockholm | 13.51.34.125 |
| 🇿🇦 Cape Town, South Africa | CapeTown | 13.244.178.74 |
| 🇧🇭 Bahrain | Bahrain | 15.184.93.28 |
Authentication
You can configure Test Agent to perform a form-based login to test logged in pages.
HTTP Headers
You can set custom HTTP headers by navigating to Site → Synthetic → Settings → Test Agent. Custom headers are applied to all Site tests.
For more granular setups, you can set custom HTTP headers to Test Profiles.
Cookies
Cookies allow bypassing authentication or turn off specific settings of your Site while testing. When you add a cookie on a Test Agent level, it will be applied to all Test Profiles for the Site.
You can also add cookies to Test Profiles to test specific scenarios.
Common questions
How does Calibre prioritise tests?
Each Calibre test is placed into a regional first-in-first-out queue with a pre-determined priority. Test Agents automatically scale on demand.
Does Calibre run tests with warm cache?
No. Tests are run using a new Chrome user profile (no cache, no prior storage), with no other known network activity, on dedicated hardware.
Is there a HTTP header to identify traffic from Calibre?
No. The best way to identify traffic from Calibre is to add the static, dedicated Test Agent IP addresses to your allow lists and protection mechanisms. Check the Test Agent IP addresses section or use automation (recommended):
- Agent JSON Endpoint.
- Calibre’s command line interface has a calibre location-list command.
- The Node.js API exports a Agent.list() function.