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Crosswalk API

CROSSWALK is the first API to network Construction Specifications Institute’s (CSI)
MasterFormat®, Uniformat®, and OmniClass® classifications with the world’s building
professionals, construction technology platforms, and data flows.

Brought to you by CSI, the creator of construction standards.

Introducing the Crosswalk API


The Crosswalk API allows integration with the Construction Specification Institute's (CSI) standards, including MasterFormat, Uniformat, and OmniClass. With Crosswalk you can easily get details of classifications, and cross-reference between different standards and versions. This portal contains everything you need to get started using the Crosswalk API.

The Crosswalk API provides a set of REST and GraphQL endpoints to query information about the entire classification database, allowing you to integrate classifications and crosswalks into any cloud or software application. Crosswalk makes it easy to implement, using REST or GraphQL endpoints and XML or JSON formatting. We also provide client SDKs in C# and NodeJS.

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Recent API Updates:

V3.1 03/02/2021

API Changes:

  • Added missing crosswalks for Standards through parents

  • Added missing crosswalks for Standards through versions


V3 11/17/2020


API Changes:

  • MasterFormat 2020 Added 

  • Performance improvements though memory management and threading optimizations

  • Classification Children no longer show obsolete versions

  • Added fields for Standards and Classifications in REST queries

  • Will not error on missing results, only return empty results



  • If you are using the NuGet package update to the latest version.

  • If you are using the NPM package update to the latest version.

  • If you are using a custom implementation change the version to v3

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