Lowvyn Public API
Canadian price intelligence as a REST API. OpenAPI 3.1, free tier, designed for ChatGPT custom GPTs and third-party developers.
What is this?
Lowvyn tracks daily prices across Amazon.ca, Walmart.ca, and Best Buy Canada, scores every product 0 to 100, and flags fake sales using full historical price data.
This is the REST surface. Same data as the MCP server (com.lowvyn/mcp), over plain HTTP+JSON for tools that don't speak MCP yet. Built for ChatGPT custom GPT actions, Perplexity, server-side integrations, and third-party developers.
Quick start
- Email contact@lowvyn.com with a one-line description of your integration. Free tier granted by default.
- Receive an API key prefixed with
lk_live_. Store it securely; it's shown to you once. - Call any endpoint with
X-API-Key: lk_live_…orAuthorization: Bearer lk_live_….
OpenAPI 3.1 spec
The full machine-readable spec lives at the URLs below. Both are public, no auth required. Use the JSON form when configuring ChatGPT custom GPT actions (which only accept JSON).
# YAML (canonical)https://api.lowvyn.com/api/public/v1/openapi.yaml
# JSON (for ChatGPT custom GPT actions)https://api.lowvyn.com/api/public/v1/openapi.json
Endpoints
Seven read-only GET endpoints. Every response includes a canonical lowvyn.com URL so AI consumers attribute citations correctly.
GET /retailers
List Canadian retailers Lowvyn tracks (Amazon.ca, Walmart.ca, Best Buy Canada).
curl -H "X-API-Key: $KEY" https://api.lowvyn.com/api/public/v1/retailersGET /categories
List product categories with active item counts.
curl -H "X-API-Key: $KEY" https://api.lowvyn.com/api/public/v1/categoriesGET /products/search?q=&category=&max_price=&retailer=
Free-text search across product titles. Sorted by current price ascending.
curl -H "X-API-Key: $KEY" "https://api.lowvyn.com/api/public/v1/products/search?q=graco%20crib&max_price=300"GET /products/{id}
Look up a product by Lowvyn ID. Returns title, current price, Lowvyn Score, Deal Verdict.
curl -H "X-API-Key: $KEY" https://api.lowvyn.com/api/public/v1/products/abc123def456GET /products/{id}/cheaper
Find the same product at other Canadian retailers via UPC matching, with savings.
curl -H "X-API-Key: $KEY" https://api.lowvyn.com/api/public/v1/products/abc123def456/cheaperGET /products/{id}/price-history?days=N
Daily (date, price) points, up to 365 days, sorted oldest to newest.
curl -H "X-API-Key: $KEY" "https://api.lowvyn.com/api/public/v1/products/abc123def456/price-history?days=90"GET /deals/verify?url=&claimed_price=
Verify whether a claimed price is a real deal versus historical lows / highs. Accepts a retailer URL.
curl -H "X-API-Key: $KEY" "https://api.lowvyn.com/api/public/v1/deals/verify?url=https%3A%2F%2Fwww.walmart.ca%2Fip%2F123&claimed_price=199.99"Example response
GET /products/{id} returns:
{
"id": "abc123def456",
"title": "Graco Benton 5-in-1 Convertible Crib",
"provider": "amazon",
"retailerUrl": "https://www.amazon.ca/dp/B0B5JMV9QB",
"currentPrice": 255.97,
"currency": "CAD",
"lowestPrice": 235.97,
"highestPrice": 299.99,
"lowvynScore": 62,
"priceSignal": "average",
"dealVerdict": "modest_deal",
"canonicalUrl": "https://lowvyn.com/product-detail/abc123def456"
}Error model
REST-idiomatic. HTTP status codes carry the success/failure signal. Error body shape:
{"error": "not_found", "message": "item \"ghost\" not found"}| Status | When |
|---|---|
| 200 | Success. |
| 400 | Missing or malformed query parameter. |
| 401 | Missing, invalid, or revoked API key. |
| 404 | Item / category / retailer not found. |
| 429 | Rate limit exceeded. Retry after the seconds in the Retry-After header. |
Privacy and rate limits
- No personal data. We log API key usage (count, timing, error class) for operational telemetry. We do not log query parameters, request bodies, or anything personally identifiable about your end users.
- Free tier rate limits. 600 requests per minute and 10000 per day per API key. Heavy hitters get HTTP 429 with a Retry-After header. Partner tiers with higher limits available on request.
- Coverage. Canadian retailers only (Amazon.ca, Walmart.ca, Best Buy Canada). Currently focused on baby products; expanding over time. All prices in CAD.
- Stability. v1.x.y semver. Breaking changes only with a major version bump. Tool/endpoint additions or optional fields are backwards-compatible and don't bump the major.
Frequently asked questions
What is the Lowvyn Public API?
A read-only HTTP+JSON API exposing Lowvyn's Canadian price intelligence (Amazon.ca, Walmart.ca, Best Buy Canada). Same data the MCP server (com.lowvyn/mcp) exposes, in a transport ChatGPT custom GPT actions, Perplexity, and third-party developers already speak.
How do I get an API key?
Email contact@lowvyn.com with a one-line description of how you'll use the API. Free tier (600 req/min, 10000/day) is granted by default. Higher partner tiers available on request.
What is the OpenAPI spec URL?
https://api.lowvyn.com/api/public/v1/openapi.yaml (canonical YAML) or https://api.lowvyn.com/api/public/v1/openapi.json (auto-converted JSON for ChatGPT custom GPT actions). Both are public, no auth required to read the spec.
Does the Lowvyn Public API cost anything?
No. Phase 2 is free for non-commercial and ethical commercial use. Higher partner tiers (above the free 600/min, 10000/day caps) are available on request.
What are the rate limits?
Free tier: 600 requests per minute and 10000 per day per API key. Returns HTTP 429 with Retry-After header on overrun. Higher tiers available for partners.
How do I authenticate?
Send your API key in either the X-API-Key header or Authorization: Bearer header. Both work identically.
What retailers does the API cover?
Amazon.ca, Walmart.ca, and Best Buy Canada. All prices in CAD. Currently focused on baby products; expanding over time. Use GET /retailers for live counts and freshness.
Are POST/PUT/DELETE supported?
No. v1 and v2 are GET-only. Write actions (track product, set price alert, submit deal) are scoped to logged-in users and arrive in Phase 3 with OAuth.
How does this relate to the MCP server?
Same data, different transport. The MCP server (com.lowvyn/mcp) is for AI assistants that speak the Model Context Protocol natively. This REST API is for everything else (ChatGPT custom GPT actions, Perplexity, server-side integrations, third-party developers). Pick whichever fits your stack.