Earnings call APIs compared: Polygon vs Finnhub vs EODHD vs Spoken Alpha

A “separate license required” row doesn't mean the data is unusable — it means you can't legally resell signals derived from it without a separate negotiated license. Read the ToS before you build a product on top.

Polygon rebranded to Massive in October 2025. URLs on polygon.io redirect to massive.com; existing API keys keep working. We'll call it Polygon throughout — that's what developers still Google.

Polygon's product is high-quality US market data: real-time WebSocket trades and quotes, deep tick history, options chains. It is genuinely good at what it does. It is also frequently misidentified as an earnings-data vendor, which it largely isn't.

Best for:real-time US market data, options, and tick history for internal trading systems or applications that don't redistribute. Not a fit if you need transcripts or want to resell derivative signals.

Finnhub is the broadest “everything financial in one API” vendor on this list. They cover quotes, fundamentals, news, alt-data, ESG, insider trades — and earnings call transcripts. They're also the only vendor in this comparison that actually sells transcript data.

That single fact is why Finnhub shows up on every “best earnings API” listicle. It's mostly correct. The honest weakness is what happens when you try to build a product on top.

Best for:prototyping with a free tier; getting transcripts at a much lower price point than S&P or Refinitiv if you can live with the ToS and the unknown source quality.

EODHD is what we use for prices, fundamentals, and the earnings calendar. We picked it after comparing it head-to-head with Polygon, and the deciding factor was a mix of breadth and the existence of a clear commercial-licensing pathway — not because the self-serve $99.99/mo plan grants commercial rights. It doesn't, and we want to be clear about that because the internet is full of writeups that get it wrong.

Best for: building research, screening, or backtest infrastructure that needs broad international coverage and clean historical data at predictable cost. If you can plan for a commercial-license uplift when you go to market, the pathway is unusually clear for this segment.

We sit on top of the previous three, not next to them. Spoken Alpha doesn't sell raw market data, fundamentals, or even the transcripts themselves. We sell an interpretive signal layer on earnings calls: per-speaker language deviation, hedging detection, tone shifts vs. that company's own historical baseline. The inputs are transcripts and prices from elsewhere; the output is a score you can act on or feed into another model.

We're going to be specific about what we are and aren't, because being unspecific is what makes most vendor pages useless.

Status (May 2026): pre-backtest, B2B early access. We are not a production-mature vendor yet. The signal taxonomy is documented, the ingestion pipeline runs, and we have a corpus we're building scoring on top of. We have not published backtested returns, and we will not until we have data we'd stake our reputation on. If a salesperson elsewhere is telling you their NLP signal is “proven on 10 years of data,” ask them to show you the methodology — most of those claims don't survive scrutiny.

Pricing: custom, B2B early access. Request access and we'll tell you what we charge in the context of what you're trying to do. We'd rather quote honestly than publish a tier table we don't yet have conviction in.

Best for: quant teams, analysts, and product builders who already have prices and transcripts and want a defensible interpretive layer on top — and who are willing to evaluate a new vendor on methodology rather than a marketing claim.

A decision tree if you've read this far:

• You need raw market data + fundamentals at low cost, broad international coverage → EODHD. Plan for a commercial license uplift if you ship a product on top.
• You need real-time US quotes, options chains, or tick-level history → Polygon (Massive). Don't expect transcripts, and budget for a commercial license if you redistribute.
• You need a free tier for prototyping, or the cheapest path to US earnings call transcripts → Finnhub. Read the ToS before building anything commercial, and spot-check transcript quality before committing.
• You need interpretive signal on call language, on top of data you already have → Spoken Alpha. Early-access fit if you're comfortable evaluating a pre-backtest vendor on methodology.
• You need real-time tick data, fundamentals, transcripts, AND signal, from one vendor → that vendor does not exist. Stack two or three of the above.

Spoken Alpha is meant to be added next to a market-data vendor, not instead of one. A typical integration looks like:

1. Keep your existing market data.If you already use EODHD, Polygon, or Finnhub for quotes and fundamentals, keep them. We don't replace that layer.
2. Decide on a transcript source. Options: license from Finnhub, bring your own scraping, or use ours (we ingest from public IR pages where rights permit, plus partnered sources).
3. Pipe earnings events to our scoring endpoint. Post-call, we return per-speaker deviation scores, hedging metrics, and call-level summaries keyed to ticker + fiscal period.
4. Join scores to your existing price data by ticker and event date. Backtest, validate, and decide what to do with the signal in your strategy or product.
5. Talk to us about redistribution rightsbefore you ship. We write that into the contract; you don't have to negotiate it later.

The total stack ends up looking like: EODHD or Polygon for prices and fundamentals, Finnhub or partnered sources for transcripts, Spoken Alpha for the interpretive layer. Three vendors, each doing one thing well, beats one vendor doing four things adequately.

Most vendor comparison pages exist to push you toward whoever wrote them. We are obviously not exempt from that — we wrote this one and we'd like you to consider Spoken Alpha. The reason we're going to the trouble of being specific about our own weaknesses (pre-backtest, US-only, B2B-only) is straightforward: you can find that out from us up front, or you can find it out three weeks into a pilot. We prefer the first version because it leads to evaluations we can actually win on the merits.

If you spot something wrong on this page — a stale price, a misread ToS, a vendor change we missed — email us. We'll fix it and credit you if you want.