79 US-code-grounded calculators across 16 categories, plus a codes reference vertical with 830 hand-curated IRC/IBC/NEC/IECC/IPC sections + adoption matrix. MCP server included. Self-signup in 60 seconds — no sales call required.
Each formula traces to IRC, IBC, NEC, IECC, IPC, ACI, TMS, DOE, or a US manufacturer spec sheet (GAF, USG, TCNA, Sherwin-Williams, Rust-Oleum). No made-up coefficients.
Streamable HTTP MCP endpoint at /mcp with auto-generated
tools from Pydantic schemas. Plug Claude Desktop, Cursor, or any MCP
client; get 85+ tools (calculators + codes reference) instantly.
RFC 7807 error responses, IETF rate-limit headers, Idempotency-Key support, Stripe metered billing, Customer Portal. No surprises.
# 1. Sign up programmatically (AI-agent flow)
curl -X POST https://api.buildcalcapi.dev/v1/account/signup \
-H "Content-Type: application/json" \
-d '{"email":"[email protected]","payment_method_id":"pm_card_visa"}'
# pm_card_visa = Stripe universal test card (free tier).
# Replace with a real PaymentMethod ID via Stripe Elements before going live.
# Response: { "api_key": "bcapi_...", ... } (shown once — save it)
# 2. Call your first calculator
curl -X POST https://api.buildcalcapi.dev/v1/calc/concrete/yards \
-H "Authorization: Bearer bcapi_..." \
-H "Content-Type: application/json" \
-d '{"length_ft": 10, "width_ft": 10, "depth_in": 4}'
# { "cubic_yards": 1.358, "bags_60lb": 62, "bags_80lb": 49, ... }
Same Bearer token works for both REST and MCP. Full quickstart →