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Open Data DC

Open Data DC exposes the District of Columbia government's Master Address Repository (MAR), an authoritative geocoding service for address, location, and property/unit data across DC. The MAR 2 API returns standardized addresses, coordinates, unit records, and Square Suffix Lot (SSL) identifiers so applications can validate and enrich DC addresses. Requests are authenticated with an API key issued through the DC Data Developers Portal.

Open Data DC icon

Power end-to-end data operations for your Open Data DC API with Nexla. Our bi-directional Open Data DC connector is purpose-built for Open Data DC, making it simple to ingest data, sync it across systems, and deliver it anywhere — all with no coding required. Nexla turns API-sourced data into ready-to-use, reusable data products and makes it easy to send data to Open Data DC or any other destination. With comprehensive monitoring, lineage tracking, and access controls, Nexla keeps your Open Data DC workflows fast, secure, and fully governed.

Features

Type: API

SourceDestination

  • Seamless API Integration: Connect to any endpoint as source or destination without coding, with automatic data product creation
  • Visual Composition & Chaining: Build complex integrations using visual templates, chain API calls, and compose workflows with data validation and filtering
  • API Proxy: Expose curated slices of your data securely with a secure and customizable API proxy that validates and transforms data on the fly
  • Request optimization with intelligent batching, retry, and caching to minimize API calls and costs

Prerequisites​

Before creating an Open Data DC credential, you need an API key for the Master Address Repository (MAR) 2 API. The MAR API is authenticated with an API key that Nexla sends in the Authorization header as a bearer token (Authorization: Bearer <api_key>).

To obtain an API key:

  1. Go to the DC Data Developers Portal and create a user profile.

  2. Sign in to the portal and open the API key management section to register and generate an API key for the MAR 2 API.

  3. Copy the generated API key and store it securely. You will provide this value when creating your Nexla credential.

The MAR API is a public geocoding service for DC addresses, so no additional account provisioning beyond the developer portal registration is required. For details on the available web services, request formats, and response fields, refer to the DC Data Developers Portal and the MAR Web Services documentation.

Authenticate​

Credentials required​

FieldRequiredSecretDescription
API KeyYesYesAPI key used to authenticate requests to the Open Data DC API.

Create a credential in Nexla​

  1. After selecting the data source type, click the Add Credential tile to open the Add New Credential overlay.

  2. Enter a name for the credential in the Credential Name field and a short, meaningful description in the Credential Description field.

  3. Enter your Open Data DC API key in the API Key field. This value is sent in the Authorization header as a bearer token to authenticate every request to the MAR API and should be kept confidential.

    If your API key is compromised, generate a new key in the DC Data Developers Portal and update your Nexla credential with the new value.

  4. Click the Save button at the bottom of the overlay. The newly added credential will now appear in a tile on the Authenticate screen during data source creation.

Use as a data source​

To create a new data flow, navigate to the Integrate section, and click the New Data Flow button. Select the Open Data DC connector tile, then select the credential that will be used to connect to Open Data DC, and click Next; or, create a new Open Data DC credential for use in this flow.

Endpoint templates​

Nexla provides pre-built templates that can be used to rapidly configure data sources to ingest data from common Open Data DC endpoints. Select the endpoint from which this source will fetch data from the Endpoint pulldown menu. Available endpoint templates are listed in the expandable boxes below.

[Rest API] List Locations

This endpoint template retrieves location records from the Master Address Repository for a given street address. Use this template to geocode and validate a DC address and return the matching MAR location records.

  • Provide the Address parameter — the street address to search for in the Master Address Repository (for example, 1600 Pennsylvania Ave NW). The endpoint returns the matching address records for that query.

For details on the location search request and the fields returned for each matched address, see the DC Data Developers Portal.

[Rest API] List Units

This endpoint template retrieves the unit records associated with a specific address in the Master Address Repository. Use this template to list the individual units (such as apartments or suites) for a known address.

  • Provide the MAR ID parameter — the Master Address Repository ID (MarId) of the address to look up units for. The endpoint returns the unit records tied to that address.

For details on the unit lookup request and the fields returned for each unit, see the DC Data Developers Portal.

[Rest API] List Ssls

This endpoint template retrieves the Square Suffix Lot (SSL) records associated with a specific address in the Master Address Repository. Use this template to return the property/parcel SSL identifiers for a known address.

  • Provide the MAR ID parameter — the Master Address Repository ID (MarId) of the address to look up SSLs (Square Suffix Lot) for. The endpoint returns the SSL records tied to that address.

For details on the SSL lookup request and the fields returned for each SSL record, see the DC Data Developers Portal.

Once the selected endpoint template has been configured, click the Test button to the right of the endpoint selection menu to retrieve a sample of the data that will be fetched. Sample data will be displayed in the Endpoint Test Result panel on the right, allowing you to verify that the source is configured correctly before saving.

Manual configuration​

Open Data DC data sources can also be manually configured to ingest data from any valid MAR API endpoint, including endpoints not covered by the pre-built templates, chained API calls, or custom request parameters. Select the Advanced tab at the top of the configuration screen, and follow the instructions in Connect to Any API to configure the API method, endpoint URL, date/time and lookup macros, path to data, metadata, and request headers.

Once all of the relevant settings have been configured, click the Create button in the upper right corner of the screen to save and create the new Open Data DC data source. Nexla will now begin ingesting data from the configured endpoint and will organize any data that it finds into one or more Nexsets.