When designing or choosing a commodity pricing API, one of the first architectural decisions is the query interface: REST or GraphQL. Both have legitimate advantages for pricing data, and the right choice depends on your use case. This article examines the trade-offs specifically in the context of metal and commodity pricing.
REST for Commodity Pricing
REST APIs organize data around resources and use HTTP methods to interact with them. For a pricing API, this typically means endpoints like /prices/current, /prices/historical, /grades, and /metals. Each endpoint returns a fixed response structure.
The advantages of REST for pricing data are significant. Pricing queries are predictable. You almost always want current prices filtered by metal or grade, or historical prices for a specific grade within a date range. These map naturally to REST endpoints with query parameters.
Caching is straightforward with REST. Current prices can be cached for 15 minutes, historical data can be cached indefinitely since it does not change, and grade metadata can be cached for days. HTTP caching headers handle this natively.
REST is also simpler for the majority of API consumers. Most developers have more experience with REST, and the tooling is universal. Curl, Postman, and every HTTP library in every language work without any additional setup.
GraphQL for Commodity Pricing
GraphQL lets clients request exactly the fields they need and combine multiple resource types in a single query. For pricing data, this means a client could request copper prices with grade details and historical data points all in one query.
The advantages appear when clients have diverse needs. A dashboard might want current prices for all metals with just the grade name and price. A trading system might want detailed data with source, timestamp, and ISRI code but only for specific grades. GraphQL lets each client get precisely what it needs without over-fetching or under-fetching.
GraphQL also shines when the data model has relationships. Prices belong to grades, which belong to metals. A GraphQL schema represents these relationships naturally, letting clients traverse the graph in queries.
The Practical Choice
For most commodity pricing use cases, REST is the better choice. Here is why. Pricing APIs serve a relatively simple data model. The number of entities is small (metals, grades, prices) and the query patterns are predictable. The developer experience benefits of REST, including simplicity, caching, and universal tooling, outweigh the flexibility benefits of GraphQL.
GraphQL makes more sense when you are building an internal API for a complex application with many different views of the same data, or when your data model is deeply nested and clients need to traverse relationships in unpredictable ways. A simple pricing API does not have this complexity.
How ScrapMetal API Approaches This
The ScrapMetal API uses REST with thoughtfully designed query parameters. Filter by metal or grade on the current prices endpoint. Specify date ranges and grades on the historical endpoint. The responses include all commonly needed fields so most use cases require a single API call. This keeps the integration simple while covering the vast majority of use cases without multiple round trips.