Developers

EngiToolbox API

Every calculator on EngiToolbox is available as a JSON REST endpoint. Validate designs, batch-run calculations and embed engineering maths directly in your own software.

Interactive API referenceOpenAPI spec (JSON)Create an API key
Quickstart

Create an API key from your dashboard (requires a Pro or Team plan), then call any endpoint with your key in the Authorization header:

curl -X POST https://engitoolbox.org/api/v1/stress \
  -H "Authorization: Bearer et_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{"force":1000,"area":0.01}'

Responses use a consistent envelope: { ok, calculator, version, inputs, result }. Errors return { ok: false, error, details? }.

Authentication & rate limits

Pass Authorization: Bearer et_…. Each key is bound to your plan. Requests are limited to a short-term burst (per key) and a monthly quota:

PlanPriceAPI requests / month
Free£0No API access
Pro£9–19/mo1,000
Team£49–199/mo10,000
EnterpriseCustom100,000

Exceeding the burst or monthly quota returns HTTP 429. See pricing for full plan details.

Endpoints (26)

Electrical

  • POST/api/v1/capacitor-network— Capacitor network
  • POST/api/v1/resistor-network— Resistor network
  • POST/api/v1/voltage-divider— Voltage divider
  • POST/api/v1/rc-time-constant— RC time constant

Manufacturing

  • POST/api/v1/drill-point-depth— Drill point depth
  • POST/api/v1/speeds-and-feeds— Machining speeds & feeds
  • POST/api/v1/pcd— Pitch circle diameter hole coordinates
  • POST/api/v1/punch-die-clearance— Punch & die clearance
  • POST/api/v1/limits-and-fits— ISO limits & fits
  • POST/api/v1/bolt-torque— Bolt torque & preload

Math

  • POST/api/v1/trigonometry— Right-triangle solver

Mechanical

  • POST/api/v1/stress— Axial / normal stress
  • POST/api/v1/friction— Friction force
  • POST/api/v1/centrifugal-force— Centrifugal force
  • POST/api/v1/moment-of-inertia— Area & polar moment of inertia
  • POST/api/v1/beam-section— Beam cross-section properties
  • POST/api/v1/youngs-modulus— Young's modulus / elasticity
  • POST/api/v1/hoop-stress— Pressure vessel hoop stress
  • POST/api/v1/resonance— Natural frequency & resonance
  • POST/api/v1/damping— Damped vibration response
  • POST/api/v1/beam-analysis— Beam analysis (FEM)
  • POST/api/v1/oring— O-ring seal & groove design

Physics

  • POST/api/v1/suvat— SUVAT kinematics solver

Reference

  • GET/api/v1/materials— Material properties database
  • POST/api/v1/unit-conversion— Unit conversion

Thermal

  • POST/api/v1/thermal-expansion— Linear thermal expansion

Try every endpoint live, with request/response schemas and code samples, in the interactive API reference.