Network Requirements
Workflow and Decision can integrate with external systems and services through various nodes. To ensure security and control over network traffic, the platform maintains a whitelist for both outgoing URL requests and incoming IP connections.
OPUS Platform IP Addresses
If your external server needs to receive incoming requests from our platform (for example, webhook callbacks or API integrations), you should whitelist our OPUS Platform IP addresses in your server’s firewall or security group settings.
To obtain the list of IP addresses to whitelist, contact us. The IP addresses will be provided to you directly.
Important: Ensure all provided IP addresses are whitelisted if your service needs to receive requests from our platform, as requests may originate from any of them.
Whitelisted URLs
The platform has whitelisted a set of commonly used external services that are available for use in your workflows and decisions.
Refer to Whitelisted URLs for the complete list as of date.
Requesting (Outgoing) URL Whitelist
If you need to use an external URL that is not on the whitelisted list, you must submit a whitelist request for our review. This is particularly important if you are using API and webhook nodes that need to connect to external APIs - these external endpoints must be whitelisted before they can be accessed from your workflows, else there will be Network Connection errors.
Submit your whitelist request through the Whitelist Request Form
URL Requirements
Important: All URLs submitted for whitelisting must meet the following minimum requirements:
- HTTPS Protocol: URLs must use HTTPS for secure communication (HTTP is not allowed)
- Business Justification: Provide clear justification for why the external URL is needed
Valid Examples:
- ✅
https://api.data.gov.sg/v1/endpoint - ✅
https://api.slack.com/api/chat.postMessage - ✅
https://api.external-service.com/webhooks
Invalid Examples:
- ❌
http://api.example.com/*(HTTP not allowed - must be HTTPS) - ❌ URLs without clear business justification
Note: All Singapore government URLs (*.gov.sg) are automatically whitelisted and do not require a whitelist request. Refer to Whitelisted URLs for the complete list.
Requesting (Incoming) IP Whitelist
For external systems to send incoming requests to our Platform (for example, triggering workflows via webhooks or sending data to our platform APIs), you must submit a request to whitelist your system’s IP addresses in our firewall.
Submit your IP whitelist request through the Whitelist Request Form
IP Requirements
Important: All IP addresses submitted for whitelisting must meet the following minimum requirements:
- Static IP Addresses: Only static IP addresses can be whitelisted (dynamic IPs are not supported)
- Valid CIDR Notation: IP addresses must be provided in CIDR notation (e.g.,
203.0.113.45/32) - Business Justification: Provide clear justification for why the external system needs to connect to our platform
- Security Contact: Provide contact information for the team responsible for the external system
Valid Examples:
- ✅
203.0.113.45/32(single IP address) - ✅
198.51.100.0/24(IP range with business justification) - ✅
192.0.2.10/32,192.0.2.11/32(multiple static IPs)
Invalid Examples:
- ❌ Dynamic IP addresses or residential IPs
- ❌ IP ranges without clear business justification
- ❌ IP addresses without proper CIDR notation
Troubleshooting
Connection Blocked
Error: “Unable to connect to external URL”
Cause: URL is not whitelisted
Solution:
- Check the Whitelisted URLs page
- If not listed, submit a whitelist request
- Wait for approval before retrying
Authentication Failures
Error: “401 Unauthorized” or “403 Forbidden”
Cause: Invalid or missing authentication credentials
Solution:
- Verify API keys and tokens are correct
- Check authentication header format
- Ensure credentials have not expired
- Review external service documentation
