I built a Canadian sales tax API that handles all 13 provinces and territories

TrueNorth API — Mon, 28 Sep 2026 23:18:10 +0000

TrueNorth API validates a Canadian address and calculates the exact tax for it in two calls: 41 product tax categories, all 13 provinces and territories, five endpoints, one API key. Whether you sell from inside Canada or from outside it, this is the whole checkout tax flow.

Here is a real example of why the details matter. Taylor Swift's official store sells the "Life of a Showgirl" CD for $17.99 USD and charges a BC buyer $18.89 total, which is $0.90 of tax. The correct BC total is $20.15, which is $2.16 of tax ($0.90 GST plus $1.26 PST). The store is a US seller collecting federal GST but not BC's 7% PST, so every BC order under-collects by exactly 7%. Details like that are exactly what TrueNorth API handles.

What it does

Five endpoints, one API key in the TrueNorthAPI-API-KEY header:

GET /calculate-tax — exact tax for a price, province, and product category
GET /classify-product — send a plain product description, get back the tax category
GET /tax-categories — list all 41 product tax categories
POST /validate-address — Canadian address validation, valid or invalid with one short reason
GET /shipping-check — deliverability check, warns on remote surcharge postal codes

The classifier understands ordinary wording. "organic cotton baby onesie" lands in children's clothing, "pre owned civic" lands in private used vehicles. Unknown products fall back to fully taxable, never under-collected.

The quirks it knows

A few examples from the 41 categories across all 13 provinces and territories: basic groceries, prescription drugs, and feminine hygiene are zero-rated federally. Manitoba exempts children's clothing up to a $150 per-item cap. Ontario rebates the provincial HST portion on prepared food under $4. Quebec's QST is charged on the GST-exclusive price, not compounded. Nova Scotia runs 14% HST. New vehicles over $100,000 attract the federal luxury tax. These are the details that generic rate tables miss.

Try it

curl "https://prsorfaeexugwkvjuwzw.supabase.co/functions/v1/canadian-api/calculate-tax?province=BC&amount=17.99&description=compact%20disc" \
  -H "TrueNorthAPI-API-KEY: your_key_here"

Tax plus address, one flow

Tax depends on the province, and the province comes from the address. Whether you sell from inside Canada or from outside it, the flow is the same: validate the customer's address, take the province code from the response, and calculate the tax.

# 1. validate the address, get back the province
curl -X POST "https://prsorfaeexugwkvjuwzw.supabase.co/functions/v1/canadian-api/validate-address" \
  -H "TrueNorthAPI-API-KEY: your_key_here" \
  -H "Content-Type: application/json" \
  -d '{"address": "123 Main St, Vancouver, BC V6A 1A1"}'

# 2. calculate tax for that province
curl "https://prsorfaeexugwkvjuwzw.supabase.co/functions/v1/canadian-api/calculate-tax?province=BC&amount=17.99&description=compact%20disc" \
  -H "TrueNorthAPI-API-KEY: your_key_here"

The address endpoint returns valid, one short reason when it is not, plus the province_code and a remote flag when the postal code checks out. That is the whole checkout tax flow in two calls.

Free tier is 10 calls a day, no card required. Pro is $19 CAD a month for 10,000 calls, Scale is $49 for 100,000.

If you sell into Canada and your checkout guesses at taxes, stop guessing: https://truenorthapi.ca

DEV Community: TrueNorth API

I built a Canadian sales tax API that handles all 13 provinces and territories

What it does

The quirks it knows

Try it

Tax plus address, one flow