Let’s clear something up right away: ExchangeRatesData API, Fixer, and Currencylayer are all built by APILayer.
So, if you came here expecting a head-to-head battle between completely different providers, that’s not really what this is. It’s more like choosing between three tools from the same toolbox.
That’s exactly why this comparison is useful.
If you’ve ever searched for something like “Fixer vs Currencylayer” or “best currency API comparison”, you’ve probably ended up jumping between three different docs pages, trying to figure out what actually makes them different. On the surface, they look very similar. Same company, similar features, overlapping use cases.
But once you dig in, the differences start to show up in ways that actually affect your integration:
- How endpoints are structured
- What the response JSON looks like
- Whether you can change the base currency on the free tier
- Which features are locked behind paid plans
None of these APIs are “better” or “worse” in a vacuum. They’re built on the same infrastructure, with the same level of reliability. The real question is: which one fits your project cleanly without friction?
That’s what this guide is here to answer.
Instead of making you dig through three separate documentation sites, this currency API comparison breaks down everything in one place. You’ll see how ExchangeRatesData API, Fixer, and Currencylayer compare in terms of endpoints, pricing, response formats, and real-world use cases, so you can pick the right one and start integrating in minutes.
Table of Contents
Key Takeaways
- All three APIs come from APILayer
This isn’t a competition between unrelated providers. They share the same infrastructure and reliability. The real difference is how each one is designed and how it fits your workflow. - Start with the ExchangeRatesData API if you’re building something new
It has the most modern design, flexible base currency support on paid plans, and a cleaner overall developer experience. - Stick with Fixer if you’re already using it
It’s stable, widely adopted, and well-documented. If it works for your current setup, there’s no urgent reason to switch. - Use Currencylayer if you want a simple, USD-based approach
It’s straightforward and predictable, especially if your application is fine working with USD as the base currency. - The biggest differences show up in small details
Things like response format (rates vs quotes), base currency limitations, and free tier restrictions can impact your integration more than you’d expect. - The fastest way to decide is to try them
All three offer free tiers, so you can test each one and see which fits your project best in just a few minutes.
Choosing Between the Three APIs
Before we get into tables and code, it helps to understand the characteristics of each API. Even though they’re all built by APILayer, they were designed with slightly different priorities in mind.
This should help you quickly figure out which one fits your project.
ExchangeRatesData API: Modern and Flexible
If you’re starting a new project today, this is the one that will feel the most natural.
ExchangeRatesData API is the newer option in the lineup, and it shows in the design. The endpoints are clean, the structure is consistent, and you’re not boxed into rigid defaults like a fixed base currency.
What stands out:
- Flexible base currency support (even on lower tiers)
- Modern endpoint design that’s easy to reason about
- Broad feature set: latest, historical, convert, time-series, fluctuation
- Cleaner JSON structure compared to older APIs
In practice, this means less friction when you’re building something like a checkout system, pricing engine, or anything that needs dynamic currency handling.
Best fit: New projects, production systems, and anything where flexibility matters.
Fixer: The Legacy Favourite
Fixer has been around the longest, and a lot of developers have used it at some point.
Because of that, it has a large user base, plenty of tutorials, and a reputation for being reliable. But it also reflects an older design philosophy, especially when it comes to base currency limitations and feature access on the free tier.
What stands out:
- Mature and widely adopted
- Strong ecosystem of guides and examples
- EUR as the default base currency (on free tier)
- Some features locked behind paid plans
If you’re already using Fixer and it’s doing the job, there’s usually no strong reason to migrate. But if you’re starting fresh, you might notice some limitations pretty quickly.
Best fit: Existing projects, legacy systems, or teams already familiar with it.
Currencylayer: Simple and USD-Focused
Currencylayer takes a different approach: keep things simple and center everything around USD.
Instead of offering full flexibility, it leans into a predictable structure. If your use case aligns with that, it can actually make your integration easier.
What stands out:
- USD as the base currency
- Straightforward and consistent response format (quotes)
- Easy to integrate for simple use cases
- Less flexible than newer alternatives
This makes it a good option for dashboards, lightweight apps, or scenarios where USD is already your reference point.
Best fit: Simple applications, USD-based workflows, and quick integrations.
Side-by-Side Comparison
Now that you have a feel for how each API is designed, let’s look at the differences that actually matter when you’re integrating one into your project.
All three APIs come from APILayer, so reliability and infrastructure are consistent across the board. What changes is how much flexibility you get, how the data is structured, and what’s included in the free tier.
Here’s a practical, developer-focused comparison:
Feature | ExchangeRatesData API | Fixer | Currencylayer |
Supported Currencies | 200+ | 170+ | 160+ |
Base Currency (Free Tier) | EUR | EUR | All Base Currencies |
Base Currency (Paid Plans) | Flexible | Flexible | Flexible |
Latest Rates Endpoint | /latest | /latest | /live |
Historical Data | Yes | Yes | Yes |
Conversion Endpoint | Paid-Tier | Yes | Yes |
Time-Series Data | Paid-Tier | Paid-Tier | Paid-Tier |
Fluctuation Data | Paid-Tier | Paid-Tier | Paid-Tier |
HTTPS (Free Tier) | Yes | Yes | Yes |
Rate Limits (Free Tier) | Limited | Limited | Limited |
Update Frequency | Tier-based | Tier-based | Tier-based |
What Actually Matters Here
At a glance, these three APIs look very similar, but a few key differences can impact how easy your integration is and what you can do on the free tier.
- Base currency flexibility can be a deciding factor
Both ExchangeRatesData API and Fixer default to EUR on the free tier, while Currencylayer supports flexible base currencies (though it defaults to USD). If your app needs a non-EUR base without upgrading, Currencylayer gives you that flexibility out of the box. - Supported currencies vary slightly
All three cover the major currencies, but ExchangeRatesData API leads with 200+ supported currencies. For most projects, this won’t matter, but it can be useful if you’re working with less common currencies. - Built-in conversion isn’t available everywhere
Fixer and Currencylayer include a conversion endpoint, while ExchangeRatesData API limits this feature to paid plans. If you’re on a free tier, this could mean writing your own conversion logic. - Advanced analytics features are paid across the board
Time-series and fluctuation data are available in all three APIs, but only on paid tiers. If you need trend analysis or historical comparisons, you’ll need to factor that into your plan choice. - Endpoint naming is mostly consistent
ExchangeRatesData API and Fixer both use /latest, while Currencylayer uses /live. It’s a small difference, but something to keep in mind when switching between APIs. - No major differences in infrastructure limits
HTTPS is available on all free tiers, and rate limits and update frequency are tier-based across all three. In other words, you’re not gaining a big advantage over the others here.
At a glance, the APIs look similar. But once you factor in flexibility, endpoints, and free tier limitations, the differences become much more practical than they first appear.
API Request & Response Comparison
This is where the differences become the most obvious.
All three APIs give you exchange rate data, but the way you request it and the way it’s structured in the response can change how you write your integration. Small differences here can mean extra parsing logic or cleaner code.
Let’s look at the same operation across all three: fetching the latest exchange rates.
ExchangeRatesData API Example
Request
curl --request GET \
--url 'https://api.exchangeratesapi.io/v1/latest?base=EUR&symbols=USD%2CGBP%2CJPY&access_key=YOUR_ACCESS_KEY' \
--header 'Accept: application/json'
Response
{
"success": true,
"timestamp": 1775262546,
"base": "EUR",
"date": "2026-04-04",
"rates": {
"USD": 1.15202,
"GBP": 0.87261,
"JPY": 183.924702
}
}
What to notice:
- Clean and predictable structure
- Base currency is clearly defined (base)
- Rates are easy to access via the rates object
- Works naturally for most applications
Want to explore further? Check out the official ExchangeRatesData API documentation.
Fixer API Example
Request
curl --request GET \
--url 'https://data.fixer.io/api/latest?base=EUR&symbols=USD%2CGBP%2CJPY&access_key=YOUR_ACCESS_KEY' \
--header 'Accept: application/json'
Response
{
"success": true,
"timestamp": 1775262546,
"base": "EUR",
"date": "2026-04-04",
"rates": {
"USD": 1.15202,
"GBP": 0.87261,
"JPY": 183.924702
}
}
What to notice:
- Very similar structure to ExchangeRatesData API
- Uses the same rates object format
- Default base currency is EUR (unless changed on paid plans)
- Slightly more “traditional” structure
Want to explore further? Check out the official Fixer API documentation.
Currencylayer API Example
Request
curl --request GET \
--url 'https://api.currencylayer.com/live?access_key=YOUR_ACCESS_KEY¤cies=EUR%2CGBP%2CJPY&format=1&callback=function_name' \
--header 'Accept: application/json'
Response
{
"success": true,
"terms": "https://currencylayer.com/terms",
"privacy": "https://currencylayer.com/privacy",
"timestamp": 1775262546,
"source": "USD",
"quotes": {
"USDEUR": 0.86709,
"USDGBP": 0.75643,
"USDJPY": 159.592
}
}
What to notice:
- Uses source instead of base
- Rates are stored in a quotes object
- Currency pairs are concatenated (e.g., USDGBP)
- Requires a bit more parsing compared to the others
Want to explore further? Check out the official Currencylayer API documentation.
Key Differences at a Glance
- Response structure: rates vs quotes
ExchangeRatesData API and Fixer both return a simple rates object where each currency is a key (e.g., “USD”: 1.15). Currencylayer, on the other hand, uses a quotes object with combined currency pairs like USDEUR, which requires a bit more parsing. - base vs source naming
ExchangeRatesData API and Fixer use the more intuitive base field to define the reference currency. Currencylayer uses source, which means you’ll need to handle slightly different naming in your code. - Consistency between ExchangeRatesData API and Fixer
These two are nearly identical in both request format and response structure. If you switch between them, your parsing logic will likely stay the same. - Currencylayer requires extra transformation
Because Currencylayer combines currency pairs (e.g., USDGBP), you’ll often need to split strings or map values before using them in your application. - Default base behaviour differs
Even though the structure looks similar, Fixer defaults to EUR and Currencylayer defaults to USD, while ExchangeRatesData API is generally more flexible depending on your plan.
If you’re building something quickly, these differences might seem minor. But in practice, they can affect how clean your code is, how easy it is to switch APIs later, and how much transformation you need to do before using the data.
When Should You Use Each API?
At this point, the differences are pretty clear. The real question is: which one should you actually use?
Instead of saying “it depends,” here’s a straightforward way to decide based on your situation.
Use ExchangeRatesData API if…
- You’re starting a new project from scratch
- You want a modern, clean API design
- You need access to more currencies (200+)
- You’re okay using EUR as the base on the free tier or plan to upgrade later
- You value consistency and flexibility as your app scales
This is the safest default for most new builds. It gives you room to grow without locking you into an older structure.
Use Fixer if…
- You’re already using it in production
- You rely on existing code, tutorials, or integrations
- You’re comfortable working with a EUR base (on free tier)
- You want something stable and widely used
If it’s already working for you, there’s no strong reason to switch. The structure is almost identical to newer options, just a bit more traditional.
Use Currencylayer if…
- You need flexible base currencies on the free tier
- Your application is USD-centric or multi-base by default
- You want a simple, predictable API
- You don’t mind doing a bit of extra parsing (quotes format)
This is a strong choice if base currency flexibility is critical early on and you want to avoid upgrading right away.
Quick Decision Guide
- Building something new? → Go with ExchangeRatesData API
- Maintaining an existing system? → Stick with Fixer
- Need flexible base currencies on free tier? → Choose Currencylayer
Pricing & Free Tier Considerations
At a high level, all three APIs follow a similar pricing model because they’re part of APILayer. You get a free tier to start, and then unlock more features, higher limits, and better flexibility as you move up.
That said, the details of the free tier can have a real impact on how far you can go without upgrading.
What You Get on the Free Tier
Across ExchangeRatesData API, Fixer, and Currencylayer:
- Limited number of API requests per month
- Access to the latest exchange rates
- HTTPS support (no security limitations here)
- Tier-based update frequency (not always real-time)
For basic use cases like small apps, testing, or prototypes, this is usually enough to get started.
Where the Differences Start to Matter
Even though the structure is similar, a few differences stand out:
- Base currency flexibility
- ExchangeRatesData API → EUR (free tier)
- Fixer → EUR (free tier)
- Currencylayer → supports all base currencies
If you need a non-EUR base without upgrading, Currencylayer gives you more flexibility early on.
- Conversion endpoint access
- Fixer and Currencylayer → available
- ExchangeRatesData API → paid only
Without a conversion endpoint, you’ll need to calculate conversions manually using rates.
- Advanced data features (paid across all APIs)
- Time-series data
- Fluctuation data
These are locked behind paid tiers everywhere, so there’s no “free advantage” here.
When You’ll Likely Need to Upgrade
You’ll probably hit the limits of the free tier if you:
- Need higher request volumes
- Require non-default base currencies (for some APIs)
- Want built-in conversion endpoints
- Are you building anything production-grade or customer-facing
At that point, all three APIs offer similar upgrade paths with:
- Higher rate limits
- More endpoints
- Faster update intervals
Bottom Line
The free tier is great for getting started, but it’s intentionally limited.
The key question isn’t just “which API is cheapest?” but:
Which API lets you build what you need with the least friction before you have to upgrade?
- If you want maximum flexibility early, Currencylayer has an edge
- If you’re fine with EUR-based workflows, ExchangeRatesData API and Fixer are just as viable
- If you need conversion built-in on free tier, avoid ExchangeRatesData API
In most cases, pricing won’t be the deciding factor long-term. The better choice is the API that matches your workflow now and scales cleanly as your requirements grow.
Real-World Use Cases
It’s one thing to compare features, but it’s more useful to see how these APIs fit into actual projects. Depending on what you’re building, one option will usually feel more natural than the others.
E-commerce Checkout and Pricing
If you’re building an online store that needs to display prices in multiple currencies or handle real-time conversions at checkout:
- Best fit: ExchangeRatesData API
- Why:
- Supports a wide range of currencies (200+)
- Clean rates structure makes pricing logic straightforward
- Scales well as you add regions or products
Ideal for: Shopify-style stores, global provider, dynamic pricing systems
SaaS Billing and Subscription Platforms
For SaaS products that bill users in different currencies or need to normalize pricing internally:
- Best fit: ExchangeRatesData API or Fixer
- Why:
- Predictable response format (rates)
- Easy to integrate into backend billing logic
- Stable and reliable for recurring calculations
Ideal for: Subscription billing, invoicing systems, usage-based pricing
Financial Dashboards and Analytics Tools
If you’re building dashboards that track exchange rate trends or currency performance:
- Best fit: Currencylayer (or any API with paid analytics features)
- Why:
- Simple structure for pulling live data
- Works well for USD-based reporting
- Supports historical and fluctuation data (paid tiers)
Ideal for: Trading dashboards, finance apps, reporting tools
Lightweight Apps and Side Projects
For quick builds, prototypes, or smaller apps where simplicity matters more than flexibility:
- Best fit: Currencylayer
- Why:
- Flexible base currencies on free tier
- Easy to get started quickly
- Minimal setup for basic use cases
Ideal for: Personal projects, demos, MVPs
Legacy Systems and Existing Integrations
If you’re working on an existing codebase that already uses one of these APIs:
- Best fit: Fixer
- Why:
- Widely adopted and well-documented
- No need to refactor working systems
- Compatible with older implementations
Ideal for: Maintaining or extending existing applications
The Big Picture
All three APIs come from APILayer, so they share the same foundation. The difference is how well they match your specific use case.
- Need flexibility and scalability → ExchangeRatesData API
- Need stability and familiarity → Fixer
- Need simplicity or flexible base currencies early → Currencylayer
In most cases, your use case will naturally point you toward one of these. The goal isn’t to find the “best” API overall, but the one that fits your project with the least amount of friction.
Getting Started
The fastest way to decide which API works best for you is to try it. All three are available through APILayer, and you can be up and running in just a few minutes.
Here’s a simple way to get started:
- Create an APILayer Account
Head over to the provider and sign up for a free account. Once you’re in, you’ll be able to subscribe to any of the three APIs.
After subscribing, you’ll get an API key. This is what you’ll use to authenticate your requests.
- Make Your First Request
Here’s a quick example using ExchangeRatesData API:
curl --request GET \
--url 'https://api.exchangeratesapi.io/v1/latest?base=EUR&symbols=USD%2CGBP%2CJPY&access_key=YOUR_ACCESS_KEY' \
--header 'Accept: application/json'
If everything is set up correctly, you’ll get a JSON response with the latest exchange rates.
- Plug It Into Your App
Once you’ve picked an API:
- Store your API key securely
- Call the endpoint from your backend
- Parse the response (rates or quotes)
- Use the data for pricing, conversions, or analytics
Quick Tip
Don’t overthink the decision upfront.
Because these APIs are so similar, the best approach is to:
- Start with one (ideally ExchangeRatesData API for new projects)
- Build a small prototype
- Switch if something feels limiting
- Check out the Quickstart Guide for more help
You can go from signup to your first working API call in under two minutes, which makes experimenting with all three a no-risk way to find the best fit for your project.
FAQ Section
- Which currency API should I use?
There isn’t a single “best” option for every use case.
- For new projects, ExchangeRatesData API is usually the best starting point
- For existing systems, Fixer is a safe choice
- For flexible base currencies on the free tier, Currencylayer stands out
- What’s the main difference between Fixer and Currencylayer?
The biggest differences are:
- Base currency defaults (EUR vs USD)
- Response format (rates vs quotes)
- Structure and parsing complexity
Fixer uses a more traditional format, while Currencylayer uses combined currency pairs like USDGBP.
- Can I switch between these APIs later?
Yes. Since all three APIs come from APILayer and share similar structures, switching is relatively straightforward. The main adjustments will be:
- Endpoint URLs
- Response parsing (rates vs quotes)
- Do all APIs support historical data?
Yes. ExchangeRatesData API, Fixer, and Currencylayer all support historical data. However, more advanced features like time-series and fluctuation data are typically only available on paid plans.
- Do I need a paid plan to use these APIs?
No. All three APIs offer free tiers that are great for:
- Testing
- Prototypes
- Small applications
You’ll only need to upgrade if you require higher limits, advanced features, or production-level usage.
Conclusion
At first glance, ExchangeRatesData API, Fixer, and Currencylayer look almost identical. And in many ways, they are. They’re all built and maintained by APILayer, they share the same infrastructure, and they all provide reliable exchange rate data.
But once you start building, the differences show up where it actually matters:
how flexible the API is, how the data is structured, and what you can do without upgrading.
If you’re starting fresh, ExchangeRatesData API is usually the easiest choice. It has the most modern design, the widest currency coverage, and a structure that scales well as your project grows.
If you’re already using Fixer, there’s no urgent reason to switch. It’s stable, widely used, and still does the job well.
And if you need flexible base currencies on the free tier, Currencylayer can be a strong option, especially for simpler or USD-centric workflows.
There’s no “wrong” choice here. The goal is to pick the API that fits your project with the least friction.
All three APIs offer free tiers, so the fastest way to decide is to try them.
Sign up for an APILayer account, grab an API key, and make your first request in under two minutes. If you’re starting fresh, we recommend beginning with ExchangeRatesData API for its modern endpoint design and flexibility.
Get your free API key here → https://apilayer.com/provider/exchangerates_data-api
