Building a currency exchange rate API usually means managing backend servers, databases, and scaling infrastructure to handle spikes in traffic. exchange-api takes a different route: it serves up currency exchange rates entirely through static JSON files hosted on CDNs, eliminating traditional backend servers and rate limits.
What exchange-api does and how it’s built
exchange-api is a lightweight, serverless RESTful API that provides real-time and historical currency exchange rates for over 200 fiat currencies, cryptocurrencies, and precious metals. Instead of dynamically generating responses, it hosts prebuilt JSON files representing exchange rate snapshots on jsDelivr CDN and Cloudflare Pages.
The architecture is straightforward yet clever: the API endpoints correspond to paths serving static JSON files. For example, you can query the latest rates or specify a date (YYYY-MM-DD) to retrieve historical data. These files are updated daily, ensuring reasonably fresh data without the complexity of real-time backend computations.
By relying on CDN hosting, exchange-api benefits from global distribution, caching, and very low latency. The dual-CDN fallback strategy uses jsDelivr as the primary CDN and Cloudflare Pages as a secondary, increasing availability and fault tolerance.
Under the hood, this means no backend servers, no databases, and effectively no rate limits since requests hit CDN caches rather than a traditional API server. The tradeoff is that data freshness is limited to daily updates, and no real-time queries or custom computations are possible.
The architecture strengths and tradeoffs
What sets exchange-api apart is its serverless, static file approach to an API usually handled by dynamic backend services. This design offers several advantages:
Zero rate limits: Since the API is just static files on a CDN, there are no server resources to exhaust or throttle. You can make as many requests as you want.
Blazing fast response times: Serving files from globally distributed CDNs means latency is minimal, often a few milliseconds.
Simplified infrastructure: No backend code to maintain, no database migrations, no scaling concerns.
High availability: The dual-CDN fallback means if one CDN is down, the other can serve the files.
However, this approach has clear limitations and tradeoffs:
Data update frequency: Rates are updated once daily, so the API isn’t suitable for intraday or real-time exchange rate needs.
No custom queries: You can’t ask for conversions or aggregated data on the fly; you get what the static files provide.
Limited extensibility: Adding new features that require dynamic behavior would break the static file model.
Data size and cache invalidation: Maintaining and distributing large JSON files for many currencies and dates might impact caching strategies and storage costs.
The codebase itself is surprisingly minimal because it mostly involves generating and uploading JSON files to the CDN. The RESTful endpoint structure is intuitive, mapping URL paths directly to JSON files.
Explore the project
If you want to understand or contribute to exchange-api, the GitHub repo is your starting point. The README details the API endpoints and the data update process.
You’ll find the scripts or workflows responsible for generating the JSON files and pushing them to the jsDelivr and Cloudflare Pages CDNs. These parts are crucial since they handle the daily data refresh.
The API usage is straightforward — you hit the JSON endpoints directly in your client code. For example:
GET https://cdn.jsdelivr.net/gh/fawazahmed0/exchange-api@latest/api/latest.json
or for a specific date:
GET https://cdn.jsdelivr.net/gh/fawazahmed0/exchange-api@2023-05-10/api/2023-05-10.json
The README also lists the supported currencies, including common cryptocurrencies and metals, which is useful when building a client application.
Verdict
exchange-api is a neat example of applying a serverless, static-file approach to an API domain that typically demands dynamic backends. Its architecture is suitable when your use case can tolerate daily data updates and doesn’t require real-time conversions or complex queries.
For developers or projects needing a free, zero-rate-limit currency exchange API with very low latency and high availability, exchange-api offers an elegant, maintenance-light solution.
That said, if you require up-to-the-minute exchange rates or complex currency conversions, this pattern will fall short. Also, extending the API with new dynamic features would require reintroducing backend logic, moving away from the static CDN model.
In production environments where cost, simplicity, and scaling are priorities over real-time data, exchange-api’s approach is worth understanding and potentially adopting.
→ GitHub Repo: fawazahmed0/exchange-api ⭐ 2,316 · Python