5 Best APIs for Time-series data in Nigeria

FastForex is a currency exchange rate API providing current and historical mid-market rates across 150+ world currencies plus common commodities (gold, silver), aimed at applications needing straightforward rate data without the tick-level bid/ask granularity that dedicated trading-focused forex APIs (like 1Forge) provide. A single GET request returns either the latest rates for a base currency against all others, or a direct conversion between two specific currencies with the amount already calculated. The API supports historical rate lookups for a specific past date (useful for financial reporting or reconciling a transaction against the rate at the time it occurred) and time-series data over a date range for building rate-history charts. Response times are optimized to be fast (as the name suggests) since the primary use case is real-time display in checkout flows, invoicing tools, and price converters rather than algorithmic trading. For Nigerian e-commerce platforms displaying prices in multiple currencies, invoicing tools converting NGN amounts for international clients, or expense-tracking apps needing historical exchange rates for reconciliation, FastForex's simple request/response model and generous free tier make it a lower-friction choice than a full trading-grade forex API when bid/ask spread precision isn't required.

Frankfurter is a free, open-source currency exchange rates API built on top of official European Central Bank reference exchange rate data. The project delivers ECB foreign exchange rates through a clean, modern REST API with no registration requirement, no API key, and no rate limits documented — offering a completely frictionless entry point for developers who need reliable currency conversion data powered by one of the world most authoritative central bank rate sources. The European Central Bank publishes official reference exchange rates for 32 currencies against the Euro on each business day at approximately 16:00 CET. These reference rates are computed from the aggregate of market rates reported by financial institutions across the eurozone, making them the official benchmark for euro currency conversions in European financial reporting and compliance contexts. Frankfurter exposes these ECB rates through a straightforward REST API that makes accessing them as simple as an HTTP GET request. The latest rates endpoint returns the most recently published ECB exchange rate set for all supported currencies relative to any specified base currency. By default, rates are base EUR, but any supported currency can be used as the base by specifying it in the request parameter. This flexibility allows applications to retrieve NGN/USD, EUR/GBP, or any other combination without client-side conversion math. The response is a clean JSON object with ISO 4217 currency codes as keys and decimal rate values. Historical rates are accessible for any date from January 4, 1999, when the ECB began publishing its reference rates, through the present. This exceptional historical depth of over 25 years of official ECB rates supports the most demanding historical analysis use cases. Nigerian financial researchers studying the long-term trajectory of major currencies, academics modeling currency relationships, or developers building historical FX analysis tools for Nigerian businesses with international exposure can query any specific date or date range within this extensive archive. Time series queries retrieve exchange rates across a date range in a single request, returning a day-by-day array of rate sets between the start and end dates. This is more efficient than making individual date queries for each day in a range and enables building currency trend charts, calculating moving averages, or analyzing rate volatility across specific periods of interest. A currency conversion endpoint simplifies the most common use case by accepting an amount, source currency, and target currency and returning the converted amount directly. This eliminates client-side conversion logic for applications where only the final converted value is needed. It is important to note that Frankfurter covers 32 currencies, and the Nigerian Naira is not among them. The ECB reference rate set covers major traded currencies primarily from developed markets. For applications specifically needing NGN exchange rates, a dedicated currency API with NGN support would be more appropriate. However, for Nigerian businesses primarily working with EUR, USD, GBP, CHF, JPY, and other major ECB-covered currencies, Frankfurter provides official-quality rate data at zero cost. The open-source nature of Frankfurter means the complete server-side codebase is publicly available. Organizations requiring guaranteed availability, data sovereignty, or control over the rate data pipeline can self-host Frankfurter on their own infrastructure, fetching directly from the ECB and serving through their own API endpoint. This self-hosting option is particularly relevant for Nigerian financial institutions subject to regulatory requirements about external data dependencies. For Nigerian developers building personal finance tools, business productivity applications, or learning projects involving international currency handling, Frankfurter offers immediate, zero-cost access to authoritative exchange rate data that is suitable for display and educational purposes without the overhead of account management.

Open Exchange Rates is one of the most widely deployed foreign exchange rate APIs in the world, used by thousands of applications ranging from e-commerce platforms and accounting software to fintech apps and content management systems. The service provides clean, reliable JSON exchange rate data for over 200 currencies, with rates updated hourly on the free tier and in real time on paid plans. Historical data going back to 2001 is available for all supported currencies, making it one of the deepest historical forex datasets accessible through a simple API. For Nigerian developers building currency-aware applications, Open Exchange Rates provides dependable NGN rate data alongside every other major world currency. Nigeria's currency situation makes exchange rate data critically important for application developers. The Nigerian Naira (NGN) has experienced significant depreciation against the US Dollar and other hard currencies over the past decade, driven by oil price volatility, foreign exchange policy changes, and structural economic factors. Nigerian applications that deal with foreign currencies — e-commerce platforms, accounting tools, remittance services, salary calculation apps for multinational employees, and investment platforms — all need accurate, regularly updated exchange rate data to function correctly. The /latest.json endpoint is the most commonly used endpoint, returning current exchange rates for all 200+ currencies from the specified base currency. On the free plan, only USD is available as the base currency — meaning all rates are expressed as units of currency per 1 USD. The USD/NGN rate is available on the free plan. For Nigerian applications that need NGN as the base currency (showing how much USD, EUR, or GBP costs in naira terms), the Starter plan ($12/month) enables any base currency. For most Nigerian applications, the USD-base approach with client-side inversion is functionally equivalent. Historical rates are available via /historical/{YYYY-MM-DD}.json, returning exchange rates as they were on any past date. This capability is essential for Nigerian accounting software and ERP systems that need to record foreign currency transactions at the exchange rate on the transaction date — a requirement under International Financial Reporting Standards (IFRS) and a common requirement in Nigerian corporate accounting practice. With rates available back to 2001, Nigerian finance teams can reconstruct historical exchange rate data for any period their records cover. The /convert endpoint performs currency conversion: specify an amount, a from-currency, and a to-currency, and receive the converted amount at the current rate. For Nigerian e-commerce platforms that display product prices in multiple currencies, this endpoint handles the arithmetic server-side without the developer needing to fetch rates and calculate manually. The /time-series endpoint returns exchange rate data over a date range, ideal for building trend charts and calculating average rates over periods. A Nigerian corporate treasurer tracking the average USD/NGN rate over each quarter, or a Nigerian researcher analyzing the correlation between naira depreciation and inflation, can use time-series data directly without downloading and processing historical files. Open Exchange Rates also provides OHLCV (open, high, low, close, volume) daily rate data for currency pairs — useful for Nigerian forex analytics tools that need to display candlestick charts or calculate volatility metrics for currency pairs. The free plan provides 1,000 API requests per month with hourly rate updates — sufficient for a low-traffic application or prototype. The Starter plan ($12/month) provides 10,000 requests per month, unlocks any base currency, and removes the USD-only restriction. The Production plan ($97/month) provides real-time rate updates and 100,000 requests per month, appropriate for high-traffic Nigerian fintech applications. All plans use a simple app_id API key parameter with no request signing, making integration extremely quick.

FxRatesAPI is a foreign exchange rate data provider offering real-time, historical, and time-series exchange rate data for over 180 currencies through a clean REST API. The service aggregates rates from multiple financial data sources and delivers accurate exchange rates for currency conversion, price display, accounting, and financial analytics applications. For Nigerian developers and businesses building applications that deal with multiple currencies — which describes the majority of Nigerian fintech, e-commerce, and accounting software — FxRatesAPI provides reliable NGN currency data alongside all major global currencies. Nigeria's position as Africa's largest economy means that currency exchange rates are not just a technical feature — they are a core business concern. The USD/NGN exchange rate directly affects the cost of imported goods displayed on Nigerian e-commerce platforms, the naira value of remittances sent from Nigerians in the diaspora, the financial reporting of Nigerian companies with foreign currency revenues, and the investment decisions of Nigerians holding foreign currency assets. An accurate, current USD/NGN rate, updated at least daily, is a fundamental requirement for dozens of categories of Nigerian applications. The /latest endpoint returns current exchange rates for all 180+ supported currencies from a specified base currency. To get the current USD/NGN rate, a Nigerian application calls the endpoint with base=USD and receives the NGN rate in the response. The same call returns rates for EUR, GBP, JPY, and every other supported currency simultaneously — making it straightforward to build multi-currency displays that show prices in multiple currencies at once. The /convert endpoint handles currency conversion arithmetic — pass the amount, the source currency, and the target currency, and FxRatesAPI returns the converted amount at the current rate. For Nigerian e-commerce platforms that need to convert a product price from USD to NGN for display, this eliminates client-side conversion code and ensures the rate used is always current. Historical exchange rate data is available via the /historical endpoint, returning rates for any past date. This is critical for Nigerian accounting and ERP applications that need to record transactions at the exchange rate on the transaction date — a requirement for Nigerian financial reporting that must comply with both IFRS standards and FIRS (Federal Inland Revenue Service) guidelines on foreign currency transactions. The /timeseries endpoint returns exchange rate data over a range of dates with daily resolution, enabling trend analysis and charting. For Nigerian currency analytics tools, this data powers time-series charts showing the USD/NGN rate history — valuable context for Nigerians trying to understand naira depreciation trends and optimize their currency holding decisions. Fluctuation data via the /fluctuation endpoint shows the change in exchange rates over a specified period — useful for Nigerian fintech apps that want to display "the naira weakened 2.3% against the dollar this week" type of contextual information alongside current rates. The free plan provides 1,500 requests per month with daily rate resolution — sufficient for low-traffic applications where real-time rates are not critical. For applications needing hourly or minute-level rate updates (forex comparison tools, live price displays on high-traffic Nigerian e-commerce sites), the Basic plan at $9.99/month provides up to 100,000 requests and hourly resolution. The Professional plan at $29.99/month provides minute-level resolution and up to 1 million requests per month — appropriate for Nigerian fintech applications with significant user traffic. All endpoints accept a simple api_key query parameter with no request signing required, making FxRatesAPI one of the quickest currency data integrations available for Nigerian developers. Responses are JSON by default with XML available as an alternative format.

Fixer.io is one of the most widely used foreign exchange rate APIs in the developer community, providing real-time and historical exchange rate data for over 170 currencies with a track record of reliability that has made it a trusted foundation for thousands of commercial financial applications globally. Built and maintained by APilayer, Fixer.io has evolved from a simple ECB rate proxy into a comprehensive FX data service aggregating rates from financial data providers with global coverage. The API provides a latest rates endpoint that returns current exchange rates for all supported currencies against a specified base currency. On the free plan, EUR is the only available base currency — reflecting Fixer.io's origins as an ECB rate service — but paid plans unlock any currency as base including the Nigerian Naira, US Dollar, British Pound, and all other supported currencies. For Nigerian applications where showing Naira as the base currency matters for user experience, upgrading to a paid plan enables NGN-based rate tables that are immediately intuitive to Nigerian users. Historical rates are accessible through a date parameter that retrieves the exchange rates that were in effect on any past date. Fixer.io maintains an extensive historical database covering many years of past rates, enabling applications to reconstruct the Naira exchange rate history, calculate the cost of historical foreign currency transactions, or build trend analysis features. Nigerian accountants and financial controllers preparing comparative financial statements need accurate historical rates for the periods being compared, and Fixer.io provides this data reliably. The time-series endpoint enables querying exchange rates across a date range, returning rates for each day between the start and end dates in a single API response. This time-series data powers trend charts, moving average calculations, and volatility analysis. For Nigerian financial professionals analyzing currency trends to inform hedging decisions or procurement timing, time-series data provides the raw material for meaningful analysis without requiring day-by-day API queries. The fluctuation endpoint is a unique Fixer.io feature that returns the change in exchange rates between two dates, expressing both absolute change and percentage change for each currency. For Nigerian import businesses monitoring how the Naira has moved against supplier currencies over a given period, the fluctuation endpoint provides a direct comparison without requiring the client application to calculate differences from raw rate data. Currency conversion is directly supported through a dedicated convert endpoint that accepts source and target currency codes and an amount, returning the converted value calculated at current rates. This endpoint streamlines implementation for applications where only the final converted amount is needed rather than access to the underlying rate data. Fixer.io is available through a freemium model where the free plan provides access to the core functionality with EUR as the only base currency. Professional plans unlock additional base currencies including NGN, increase request frequency, and enable access to historical data, time-series, and fluctuation endpoints. The pricing is transparent and competitive with comparable FX data services, making it accessible for Nigerian fintech startups at various stages of growth. Nigerian payment processors, fintech platforms, accounting software vendors, and e-commerce developers have deployed Fixer.io as the exchange rate data backbone for their products. The API's extensive documentation, code samples in multiple languages, and the large developer community means that integration questions have usually already been answered in forums and documentation. API key authentication with straightforward query parameters and consistent JSON responses makes Fixer.io one of the fastest currency APIs to integrate into new Nigerian applications.