What is included in the API?

The API provides 1,173 construction calculators with all inputs, 3,485 published test vectors, 79 job takeoffs, building code citations, a cross-market glossary, and a corrections ledger, all as static JSON files.

Is authentication required to use the API?

No authentication key, quota or rate limit is required because there is nothing to meter. All data is freely available.

What is the licence for the API data?

The API data is published under CC BY 4.0, allowing commercial use, redistribution and modification as long as Craft Quantities is credited and linked back to.

How are calculators verified for accuracy?

Each calculator cites the building standard it uses with specific section numbers, carries pinned test cases frozen as automated tests, and undergoes site-wide reviews where every calculator is individually checked for arithmetic, units and sources.

Can the API be called from a browser?

Yes, every file carries Access-Control-Allow-Origin: * so a plain fetch works from any origin. Keep to simple GET or HEAD requests as custom headers trigger a CORS preflight.

Developer Tools

Craft Quantities

Free JSON API for construction calculators with test vectors and building codes

0 votes. Log in to give Craft Quantities a nod Follow the workshop. Log in to follow Craft Quantities's workshop

Community votes: 0
DR by Ahrefs: Not measured yet

Free static JSON API providing 1,173 construction calculators with inputs, units, test vectors and building code citations under CC BY 4.0 licence.

What it is

Screenshot of the Craft Quantities homepage — craftquantities.com, as visitors see it

Craft Quantities provides a free, open API delivering construction calculator data as JSON. The API includes 1,173 calculators covering concrete, electrical, plumbing, materials estimation and many other trades, plus 3,485 published test vectors for validation. All data is documented with citations to building codes and standards from bodies including ACI, IRC, NEC and IPC.

The API requires no authentication key or rate limiting, with data available under CC BY 4.0 licence. Alongside the static JSON files, it offers an executable API for running calculations programmatically and an MCP server for AI assistants. The site emphasizes verification through pinned test cases, cited standards with section numbers, and regular audits of calculator accuracy.

What it is built with

1,173 construction calculators with full inputs and test vectors
3,485 published test vectors for validation
No authentication key or rate limits required
Citations to building standards with section numbers
Executable API for running calculations on request
MCP server integration for AI assistants
79 job takeoffs with calculator sequences
Cross-market glossary in US, Canadian, UK and Australian usage
Corrections ledger tracking confirmed errors
Unit conversion with exact statutory factors

Pricing

Pricing model: Open source

Free under CC BY 4.0 licence

Follow the workshop. Log in to follow Craft Quantities's workshop

Following Craft Quantities means an email when they reach a milestone, post an update or launch a new product.