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Migration Guide — Xe Currency Data API → fastFOREX API

Migrate from XE Currency Data in under an hour

Xe's API is built around conversion endpoints with Basic auth and an array-shaped response; fastFOREX API uses key-header auth and flat maps. The concepts line up cleanly — this guide maps each one.

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Draft guide — endpoint mapping to be validated against both APIs' current docs before publishing.

Four steps, most of them small.

  1. Get a free API key

    7-day trial, no credit card, full plan access from minute one.

  2. Swap base URL & auth

    xecdapi.xe.com/v1 with HTTP Basic (account_id:api_key) → api.fastforex.io with a single X-API-Key header.

  3. Reshape one response

    Their to: [{quotecurrency, mid}] array becomes our flat results map — a loop becomes a lookup.

  4. Benchmark, then cut over

    Run both in parallel on the trial, compare values and latency, switch when convinced.

Endpoint mapping

Every endpoint, translated.

One row per call your code makes today. Parameters keep their meaning — only names and paths change.

Purpose

Xe Currency Data API

fastFOREX API

Latest rates from one base

GET /v1/convert_from.json?from=USD&to=EUR,GBP&amount=1

GET /fetch-multi?from=USD&to=EUR,GBP

Rates into one currency

GET /v1/convert_to.json?to=USD&from=EUR,GBP&amount=1

GET /fetch-multi per base, or invert client-side (1/rate)

Convert an amount

GET /v1/convert_from.json?…&amount=100

GET /convert?from=USD&to=EUR&amount=100

Historical (single date)

GET /v1/historic_rate.json?date=2020-01-01&…

GET /historical?date=2020-01-01

Time-series (date range)

GET /v1/historic_rate/period.json?start_timestamp=…&end_timestamp=…

GET /time-series?start=…&end=…

Monthly averages

GET /v1/monthly_average.json

Compute from /time-series (daily points)

List currencies / account

GET /v1/currencies.json · /v1/account_info.json

GET /currencies · GET /usage

Authentication

HTTP Basic — account_id:api_key

X-API-Key header

Response shapes

Before and after.

Xe returns an array of {quotecurrency, mid} objects you loop over; we return a flat results map you index into. Replace the loop with results[code] and you're done.

Before · Xe Currency Data API
$ curl -u account_id:api_key "https://xecdapi.xe.com/
   v1/convert_from.json?from=USD&to=EUR,GBP&amount=1"

{
  "from": "USD",
  "amount": 1.0,
  "timestamp": "2026-09-10T00:00:00Z",
  "to": [
    { "quotecurrency": "EUR", "mid": 0.8599 },
    { "quotecurrency": "GBP", "mid": 0.7299 }
  ]
}
After · fastFOREX API
$ curl -H "X-API-Key: YOUR_KEY" \
   "https://api.fastforex.io/fetch-multi?from=USD&to=EUR,GBP"

{
  "base": "USD",
  "results": {
    "EUR": 0.8599,
    "GBP": 0.7299
  },
  "updated": "2026-09-10T09:39:00Z"
}

Watch for these differences.

The honest list — everything that behaves differently, including the ones that work in your favour.

  1. Rate freshness is a different game

    Xe's standard packages update daily, with minutely updates sold as an add-on. fastFOREX API updates continuously on every plan — if you built polling schedules around daily data, they can go.

  2. Billing model changes

    Xe packages are annual with per-request tiers; fastFOREX API is monthly or annual with 1M calls included from $18/mo. Worth re-running the numbers on your actual volume.

  3. Licensing terms differ

    Xe licenses per legal entity with terms around redistribution. Review both providers' terms against your use case — especially if you display rates to end users.

  4. Basic auth → header key

    Retire the account_id/api_key pair for a single API key. Rotate and label keys in the Console — handy if the old credentials were shared across services.

Prove it to yourself

Benchmark both during your trial.

Don't take our 21ms average on faith. Run both APIs from your own infrastructure with this snippet, compare the numbers, and cut over when the data says so.

benchmark.sh · run from your servers
$ for i in 1 2 3 4 5; do
>   curl -s -o /dev/null -w "fastforex  %{time_total}s\n" \
>     -H "X-API-Key: KEY" "https://api.fastforex.io/fetch-all?from=USD"
>   curl -s -o /dev/null -w "xe         %{time_total}s\n" \
>     -u account_id:api_key "https://xecdapi.xe.com/v1/convert_from.json?from=USD&amount=1"
> done

fastforex  0.022s
xe         0.061s

Switching support included.

Our team answers 365 days a year and has guided many migrations from this exact provider. Need longer than 7 days to validate? Ask about extending your trial.

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Migration questions.

What teams ask when leaving Xe Currency Data API.

Can I run both APIs in parallel?
Yes — the recommended path. The 7-day trial has full plan access, so shadow-read against both providers and compare values and latency on production traffic before switching.
Will values match Xe's exactly?
Close but not identical. Xe publishes a blended mid-rate updated on its own schedule; we aggregate 100+ institutional contributors continuously. Intraday differences are normal — benchmark both against a reference you trust.
We rely on Xe's monthly averages.
Pull daily closes from /time-series and average them — a few lines of code, and you control the methodology (calendar month, business days, or your own window).
Can you help with the migration?
Yes — support answers 365 days a year. If you need more than 7 days to validate, ask about extending your trial.

Something specific to your setup?

Send us your current integration details and we'll map it for you.

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