Overview
Add or update custom properties on existing requests. Properties are key-value pairs that allow you to attach metadata, tags, or contextual information to requests after they’ve been created. This is useful for post-hoc categorization, debugging, and analytics.Endpoint
string
required
PUT
string
required
/v1/request//property
Authentication
Requires API key authentication via theAuthorization header:
Path Parameters
string
required
The unique identifier of the request to update
Request Body
string
required
The property key/name. Must be a string.Examples:
"environment""user_tier""feature_flag""conversation_id""customer_id"
string
required
The property value. Must be a string.Examples:
"production""premium""enabled""conv_123""cust_456"
Response
Returns a success or error response.null
Always
null on successstring
Error message if the request failed, otherwise
nullExamples
Add Single Property
Add an environment tag:Update Existing Property
Update a property value (same key, new value):Add Multiple Properties
Add multiple properties by making multiple requests:Using in Code
Response Examples
Success Response
Error Response
Use Cases
Post-Processing Categorization
Tag requests after analysis:Customer Tracking
Link requests to customer accounts:A/B Test Annotation
Mark requests with experiment variants:Error Classification
Tag failed requests with error categories:Feature Flag Tracking
Track which features were enabled:Quality Review Workflow
Manage review status:Cost Allocation
Tag requests for cost tracking:Query by Properties
Filter requests by custom properties:Property Naming Best Practices
- Use snake_case:
customer_idinstead ofcustomerIdorCustomerID - Be consistent: Use the same property names across your application
- Namespace when needed:
feature_new_uiinstead of justnew_ui - Keep keys short:
envvsenvironment_name_and_region - Document your schema: Maintain a list of standard properties
Example Property Schema
Notes
- Properties are stored as string key-value pairs
- If a property key already exists, the value will be updated
- Properties are immediately available in queries and analytics
- Maximum recommended property key length: 100 characters
- Maximum recommended property value length: 1000 characters
- Properties can be set during request creation via Helicone headers or after the fact via this API
- Use properties in combination with feedback and scores for comprehensive request tagging
Comparison with Request-Time Properties
You can also set properties when making requests using Helicone headers:- You need to add properties after a request has been made
- Properties are determined through post-processing or analysis
- You’re categorizing or tagging historical data
- Properties depend on the response or subsequent events
- You know the properties at request time
- Properties are part of your application context
- You want to minimize API calls