Validations API #

The Validations API provides access to validation data from Project Sidewalk, where community members review and validate labels placed by other users. Each validation record includes the validator's judgment (Agree, Disagree, or Unsure), any changes made to tags or severity levels, and associated metadata.

This API is useful for researchers studying data quality, community validation patterns, and the reliability of crowdsourced accessibility data. The validation process helps ensure the accuracy and consistency of Project Sidewalk's accessibility information.

Validations API Preview #

Below is a live preview showing validation result distributions by label type, retrieved directly from the API:

Loading validation data...

Endpoint #

Retrieve validation data with optional filtering by various criteria.

GET /v3/api/validations

Examples#

/v3/api/validations Get all validations in JSON (default)

/v3/api/validations?filetype=csv Get all validations in CSV format

/v3/api/validations?validationResult=1 Get only "Agree" validations

/v3/api/validations?labelTypeId=2&changedTags=true Get validations for label type 2 where tags were changed

Quick Download #

Download validation data directly in your preferred format:

Query Parameters#

This endpoint accepts the following optional query parameters to filter validation data.

Parameter	Type	Description
`labelId`	`integer`	Filter validations for a specific label by its unique ID.
`userId`	`string`	Filter validations performed by a specific user (validator).
`validationResult`	`integer`	Filter by validation result: `1` (Agree), `2` (Disagree), `3` (Unsure).
`labelTypeId`	`integer`	Filter validations for a specific label type (e.g., CurbRamp, Obstacle). See Label Types API
`validationTimestamp`	`string`	Filter validations performed after this ISO 8601 timestamp (e.g., "2023-01-01T00:00:00Z").
`changedTags`	`boolean`	Filter validations where tags were changed (`true`) or not changed (`false`).
`changedSeverityLevels`	`boolean`	Filter validations where severity levels were changed (`true`) or not changed (`false`).
`filetype`	`string`	Output format: `json` (default), `csv`. Note: `shapefile` is not supported for validation data.
`inline`	`boolean`	Whether to display the file inline (`true`) or as a download attachment (`false`, default).

Responses#

Success Response (200 OK)#

On success, the API returns an HTTP 200 OK status code and the requested data in the specified format.

JSON Format (Default) #

Returns a JSON array containing validation objects:

[
    {
        "validation_id": 12345,
        "label_id": 67890,
        "user_id": "user_abc123",
        "validation_result": 1,
        "validation_timestamp": "2023-09-15T14:32:47Z",
        "label_type_id": 2,
        "label_type": "NoCurbRamp",
        "severity_before": 3,
        "severity_after": 4,
        "changed_severity": true,
        "tags_before": ["narrow"],
        "tags_after": ["narrow", "steep"],
        "changed_tags": true,
        "street_edge_id": 54321,
        "neighborhood_id": 15,
        "neighborhood_name": "Downtown",
        "lat": 47.6062,
        "lng": -122.3321
    },
    {
        "validation_id": 12346,
        "label_id": 67891,
        "user_id": "user_def456",
        "validation_result": 2,
        "validation_timestamp": "2023-09-15T15:45:12Z",
        "label_type_id": 1,
        "label_type": "CurbRamp",
        "severity_before": 2,
        "severity_after": 2,
        "changed_severity": false,
        "tags_before": ["wide"],
        "tags_after": ["wide"],
        "changed_tags": false,
        "street_edge_id": 54322,
        "neighborhood_id": 15,
        "neighborhood_name": "Downtown",
        "lat": 47.6065,
        "lng": -122.3318
    }
]

JSON Field Descriptions #

Field	Type	Description
`validation_id`	`integer`	Unique identifier for the validation record.
`label_id`	`integer`	ID of the label that was validated.
`user_id`	`string`	ID of the user who performed the validation.
`validation_result`	`integer`	Validation judgment: 1 (Agree), 2 (Disagree), 3 (Unsure).
`validation_timestamp`	`string`	ISO 8601 formatted timestamp when the validation was performed.
`label_type_id`	`integer`	ID of the label type (e.g., 1 for CurbRamp, 2 for NoCurbRamp).
`label_type`	`string`	Name of the label type (e.g., "CurbRamp", "Obstacle").
`severity_before`	`integer \| null`	Severity rating before validation (1-5 scale), or null if not applicable.
`severity_after`	`integer \| null`	Severity rating after validation, or null if not changed/applicable.
`changed_severity`	`boolean`	Whether the validator changed the severity rating.
`tags_before`	`array`	Array of tag names before validation.
`tags_after`	`array`	Array of tag names after validation.
`changed_tags`	`boolean`	Whether the validator changed any tags.
`street_edge_id`	`integer`	ID of the street segment where the label is located.
`neighborhood_id`	`integer`	ID of the neighborhood containing the label.
`neighborhood_name`	`string`	Name of the neighborhood containing the label.
`lat`	`number`	Latitude coordinate of the validated label.
`lng`	`number`	Longitude coordinate of the validated label.

CSV Format #

If filetype=csv is specified, the response will be CSV data with the same field structure:

validation_id,label_id,user_id,validation_result,validation_timestamp,label_type_id,label_type,severity_before,severity_after,...
12345,67890,user_abc123,1,2023-09-15T14:32:47Z,2,NoCurbRamp,3,4,...
12346,67891,user_def456,2,2023-09-15T15:45:12Z,1,CurbRamp,2,2,...

Error Responses#

If an error occurs, the API will return an appropriate HTTP status code and a JSON response body containing details about the error.

400 Bad Request: Invalid parameter values (e.g., invalid validationResult, unsupported filetype).
404 Not Found: The requested resource does not exist.
500 Internal Server Error: An unexpected error occurred on the server.
503 Service Unavailable: The server is temporarily unable to handle the request.

Error Response Body #

Error responses include a JSON body with the following structure:

{
    "status": 400,
    "code": "INVALID_PARAMETER",
    "message": "Invalid validationResult value. Must be 1 (Agree), 2 (Disagree), or 3 (Unsure).",
    "parameter": "validationResult"
}

Validation Result Types #

Project Sidewalk uses three validation result types to categorize validator responses:

ID	Name	Description
`1`	Agree	The validator agrees with the original label placement and classification.
`2`	Disagree	The validator disagrees with the original label placement or classification.
`3`	Unsure	The validator is uncertain about the label's accuracy (e.g., due to image quality).

You can also retrieve this information programmatically from the/v3/api/validationResultTypes endpoint, which includes current count statistics for each validation result type.

Data Analysis Tips #

The Validations API provides rich data for understanding community consensus and data quality. Here are some suggestions for effectively using this data:

Analyze agreement patterns by label type to identify which accessibility features are easier or harder for the community to classify consistently
Track tag and severity changes to understand how validation improves label accuracy and completeness
Use temporal filtering to study validation patterns over time
Cross-reference with user data to analyze validation behavior across different user types and experience levels
Map validation results geographically to identify neighborhoods or street types where labels are more controversial
Calculate inter-rater reliability by analyzing multiple validations of the same labels

Related APIs

For comprehensive validation analysis, consider using the Validations API alongside:

Raw Labels API - Get the original labels that were validated
Label Types API - Understand the classification system used for validations
Label Tags API - Learn about the tag system that validators can modify
User Stats API - Analyze validator behavior and experience levels
Overall Stats API - Get aggregate validation statistics

Terms of Use #

If you use Project Sidewalk data in your research, please cite the following paper (awarded 🏆 Best Paper at CHI 2019):

Manaswi Saha, Michael Saugstad, Hanuma Teja Maddali, Aileen Zeng, Ryan Holland, Steven Bower, Aditya Dash, Sage Chen, Anthony Li, Kotaro Hara, and Jon Froehlich. 2019. Project Sidewalk: A Web-based Crowdsourcing Tool for Collecting Sidewalk Accessibility Data At Scale. In Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems (CHI '19). Association for Computing Machinery, New York, NY, USA, Paper 62, 1–14. https://doi.org/10.1145/3290605.3300292

Contribute#

Project Sidewalk is an open-source project created by the Makeability Lab and hosted on GitHub. We welcome your contributions! If you found a bug or have a feature request, please open an issue on GitHub.

You can also email us at sidewalk@cs.uw.edu

Project Sidewalk in Your City!#

If you are interested in bringing Project Sidewalk to your city, please read our Wiki page.