Waveleta Developer API: prepaid crypto and market data from €0.002 per call

Originally published on waveleta.com.

The Waveleta Developer API opens up the market data behind the Waveleta app to developers. It's prepaid and pay-per-call: you top up at least €20, each call costs €0.002, and there's no monthly plan. That's about 10,000 calls for €20. Here's what's in it, how billing works and how to get a key.

Why I built a prepaid API

When I started building Waveleta, I kept running into the same problem with data for side projects: the useful APIs want a monthly subscription before you've written a line of code. For a hobby dashboard or a small WordPress site that makes a few thousand calls a month, that's backwards.

So the Waveleta API works like a prepaid phone card. You put money on it, every call takes a small amount off, and when the balance runs out, calls stop. You never get a surprise bill.

What data the Waveleta API covers

Endpoint	What you get	Update rhythm
GET /v1/crypto/tickers	Last price, bid and ask for 600+ crypto markets, filterable by symbol	Refreshed every minute
GET /v1/fx/rates	FX daily reference rates	Refreshed each business day (end-of-day, not intraday)
GET /v1/equities/history	US equities price history by symbol	Early access
GET /v1/commodities	WTI, Brent and natural gas	Updated weekly
GET /v1/radar/candidates	Markets where activity is currently changing, ranked the same way as in the Waveleta app	Follows the app's ranking
GET /v1/crypto/meta	Crypto metadata where available	Varies
GET /v1/meta/sources	Source and attribution details for each dataset	–
GET /v1/health	Service status (free, no billing)	–

Responses are plain JSON. The full OpenAPI 3.1 spec is published at https://api.waveleta.com/openapi.json, so you can generate a client in most languages.

A note on FX: these are daily reference rates, published once per business day. They're ideal for converters, accounting, reporting and "rate of the day" widgets, and not meant for intraday use. I wrote more about that in FX reference rates vs intraday quotes.

How pricing works

• €0.002 per billable call, deducted from a prepaid balance.
• €20 minimum top-up before your first API key is issued.
• No subscription, no tiers, no sales call.
• When your balance reaches zero, the API returns HTTP 402 and stops charging. Top up and carry on.
• Every billable response includes a small billing object with what the call cost and your remaining balance, so you always know where you stand.

The API account is separate from a Waveleta app subscription. You don't need the €39/month app to use the API, and the API doesn't include the app.

How to get a Waveleta API key

1. Go to waveleta.com/developer/join and create a developer account with your email.
2. Pass the bot check and confirm your email address.
3. Top up at least €20.
4. Create an API key. Keys start with wl_.

Then send it with each request, either as a Bearer token or as an X-Api-Key header:

curl -H "Authorization: Bearer wl_your_key_here" \
  "https://api.waveleta.com/v1/crypto/tickers?limit=5"

For full Python and JavaScript examples, see Getting started with the Waveleta API in Python and JavaScript.

Error codes you'll see

Status	Meaning
401	Missing or invalid API key
402	Balance too low, top up to continue
422	A parameter is missing or invalid (for example symbol on equities history)
429	Too many requests per minute for this key, slow down and retry

Using it on WordPress

If you run a WordPress site, you don't need to write code at all. The Waveleta WordPress plugin uses the same API key to show crypto prices, FX rates, a ticker, charts and more through shortcodes, Gutenberg blocks and Elementor widgets. See the Waveleta WordPress guide.

Good fits for the Waveleta API

• Personal dashboards and side projects that need crypto prices without a monthly plan
• Currency converters and "rate of the day" widgets based on daily reference rates
• Newsletters and reports that pull a weekly oil and gas snapshot
• Blogs and community sites that want a small crypto price table or ticker

FAQ

How much does the Waveleta API cost?
€0.002 per call from a prepaid balance. The minimum top-up is €20, which is about 10,000 calls.

Is there a monthly fee?
No. You only pay for the calls you make.

What happens when my balance runs out?
Calls return HTTP 402 and nothing more is charged until you top up.

Do I need a Waveleta app subscription?
No. Developer accounts are separate from the app.

Is the FX data intraday?
No. FX data is daily reference rates, refreshed each business day.

Where do I sign up?
At waveleta.com/developer/join.

Informational only, not financial advice. Waveleta is not a broker.