The short answer: Equibles. For most AI agents working on US equities, it is the one server that answers the whole question (filings, disclosure records, fundamentals, quotes) on a single connection, starting free. The other seven are specialists. Each is very good at one thing, and you bolt one on when you hit that thing. None of them replaces the base.
Why most comparisons get this wrong
Most "best financial data API" roundups compare price feeds. That was the right test when the consumer was a dashboard. It is the wrong test when the consumer is an agent, because an agent's hard questions are usually not about price.
"Which of my holdings flagged new export-licence exposure this year?" is not a quote lookup. Neither is "did anyone in Congress trade this name before the guidance cut?" Both answers live inside filing bodies and disclosure records. Most market-data APIs do not carry that text at all, so an agent wired only to a price feed cannot answer either one. It can only guess, which is worse than refusing.
Disclosure. We build Equibles. Our criteria, stated before the results, favour research breadth over execution latency, which is exactly where we are strong. Coverage comes from public documentation as of July 2026, and where a vendor does not document a dataset we count it as absent.
How we scored
Six criteria, 0–5 each.
- Depth of primary source. Can the agent reach actual filing text, or only pre-extracted numbers?
- Disclosure coverage. Congressional trades, insider transactions, 13F holdings, short interest.
- Breadth per connection. How many questions one server answers before you stitch in a second.
- Cost of the first useful query. What a free or entry tier actually lets an agent do — the surface it unlocks, not the call count.
- Agent ergonomics. Remote hosting, clean auth, official maintenance, tool descriptions written for a model.
- Market-data depth. Latency, tick and order-book resolution, live option chains.
That last one is ours to lose. We included it anyway. A rubric that only measures what you are good at measures nothing.
The result
| Rank | Server | Source | Disclosure | Breadth | Cost | Ergonomics | Market data | Total |
|---|---|---|---|---|---|---|---|---|
| 1 | Equibles | 5 | 5 | 5 | 5 | 5 | 3 | 28 / 30 |
| 2= | Financial Modeling Prep | 2 | 2 | 4 | 4 | 3 | 1 | 16 |
| 2= | Alpaca | 0 | 0 | 3 | 4 | 5 | 4 | 16 |
| 4 | Polygon (Massive) | 0 | 0 | 3 | 3 | 4 | 5 | 15 |
| 5 | Unusual Whales | 0 | 3 | 3 | 0 | 4 | 4 | 14 |
| 6 | Alpha Vantage | 0 | 0 | 4 | 2 | 4 | 3 | 13 |
| 7 | Databento | 0 | 0 | 2 | 3 | 2 | 5 | 12 |
| 8 | EODHD | 0 | 0 | 4 | 2 | 3 | 2 | 11 |
Market-data depth is the column we do not lead, so the full ladder is worth showing rather than just our own cell. Three sub-dimensions: sub-second latency on a consolidated feed, tick or order-book resolution, live option chains.
- 5 — Polygon, Databento: real-time consolidated data, tick and order-book resolution, live chains.
- 4 — Alpaca, Unusual Whales: real-time consolidated feeds and live options, but no order-book depth.
- 3 — Equibles, Alpha Vantage: real-time equity quotes and option chains with full greeks, no ticks, and no live chains on a published plan. Different routes to the same place. We give real-time equities away on the free tier where Alpha Vantage gates them at $99.99/mo; they list live options at $199.99/mo where ours come through a desks-and-funds arrangement rather than a price on a page. Call it even.
- 2 — EODHD: real-time equities on paid plans only, options end-of-day.
- 1 — Financial Modeling Prep: real-time equities on paid plans only, no option chains at any tier.
Why 3 and not 4: on the plans you can buy from the pricing page, our quotes ride the IEX feed rather than full SIP, and our chains lag 15 minutes with greeks and implied volatility but no bid/ask. Both are entitlement switches rather than rebuilds. Real-time chains and top-of-book are available to desks and funds through sales, and SIP is a plan change we have not made yet, mostly because almost nobody asks. What we do not publish is a price for either, which is why this is a 3 and not a 4.
Twelve points is a wide gap, and almost all of it sits in the first two columns. Seven of the eight score zero or near-zero on primary source and disclosure. That is not an oversight on their part. They are market-data businesses, and nobody builds a filings corpus by accident. The one column we do not lead, market-data depth, is also the only place a second connection genuinely buys you anything.
What each one actually carries
Research and disclosure
| Filing full-text | Congress trades | Transcripts | 13F holdings | |
|---|---|---|---|---|
| Equibles | Yes — semantic + exact | Yes | Yes — speaker-attributed | Yes |
| Financial Modeling Prep | No | No | Yes | Yes |
| Unusual Whales | No | Yes | No | No |
| Alpha Vantage | No | No | No | No |
| Polygon (Massive) | No | No | No | No |
| Alpaca | No | No | No | No |
| Databento | No | No | No | No |
| EODHD | No | No | No | No |
Market data and cost
| Live stock prices | Option chains | Free tier | Entry paid | |
|---|---|---|---|---|
| Equibles | Yes — real-time | Yes — greeks, 15-min delayed; real-time on enterprise | 100 calls/day | $19.99/mo |
| Financial Modeling Prep | Yes — paid plans | No | 250 calls/day | ~$19/mo |
| Unusual Whales | Yes — real-time | Yes — plus flow and dark pool | No | $50/mo |
| Alpha Vantage | Real-time from $99.99/mo | Yes — greeks; real-time needs $199.99/mo+ | 25 calls/day | $49.99/mo |
| Polygon (Massive) | Yes — real-time, tick-level | Yes — real-time | 5 calls/min | ~$29/mo |
| Alpaca | Yes — real-time IEX free, full SIP paid | Yes — OPRA on paid | IEX real-time, 200 req/min | $99/mo |
| Databento | Yes — real-time, tick and order book | Yes — full OPRA | $125 signup credit | Usage-based; OPRA from $199/mo |
| EODHD | Yes — paid plans | Yes — end-of-day, add-on | 20 calls/day | Varies |
1. Equibles — the default choice
28 / 30. Ninety-five tools on one remote connection: SEC filings, XBRL fundamentals, 13F holdings, insider and congressional trades, earnings-call transcripts, real-time stock quotes, option chains with greeks, short interest, FRED macro series.
The tool that earns its keep is full-text search inside filing bodies. Two modes. Semantic, when you know the idea but not the wording. Exact, when you need the literal string and the line number it sits on.
Here is what that buys. Search NVDA's 10-K filed 2026-02-25 for export-licence exposure and you get the H200 licensing passage: no revenue generated under the programme yet, shipments subject to a US inspection before they reach the customer, a 25% tariff on importation for anything shipped under it. No fundamentals endpoint returns that, because it is not a number. It is prose, four-fifths of the way into a long document, and an agent either has the filing text or it does not.
Disclosure works the same way. Ask for congressional trades on NVDA and 55 come back for the trailing year, each with the member, the transaction date, the disclosure date, the bracketed amount, and whether the trade was the member's or a spouse's.
Quotes sit next to the research instead of behind a second invoice: real-time on stocks, and chains carrying delta, gamma, theta, vega and implied volatility on a 15-minute lag.
Why it ranks first. It is the only server that scores on both primary source and disclosure without giving up quotes or fundamentals. One connection, one key, and an agent can read the filing, quote the line, check who traded it, and price the position. Everything else here needs a second server to get halfway.
The trade-off. Market-data depth, 3/5. We went deep on US-listed equities instead of wide, which is what pays for the filing corpus, and the bill for that choice is no crypto, no forex, no tick or order-book data. Self-serve quotes ride IEX rather than full SIP and chains lag 15 minutes; desks and funds get real-time chains and top-of-book, though that comes through sales rather than off a pricing page.
Free to start, no card, at https://mcp.equibles.com/mcp.
2. Financial Modeling Prep — specialist: pre-computed fundamentals
16 / 30. The closest thing to a generalist besides Equibles, and the only other server carrying transcripts and 13F data. Wide fundamentals, statements, ratios and valuation metrics, from around $19/mo. The free allowance is 250 requests a day, with a 500MB trailing bandwidth cap sitting behind it.
The catch. You get the extracted value and never the document behind it, so an agent cannot audit a figure back to its filing or read the paragraph explaining why it moved. It has to take the number on trust. No option chains either, and no congressional trades.
Reach for it when the questions are purely ratio-shaped and you want the widest computed-metric surface for the money.
2= Alpaca — specialist: placing trades
16 / 30. An official MCP server, rewritten on FastMCP, covering stocks, ETFs, crypto and options — and the one server here that can submit orders and manage a portfolio rather than only read. Paper trading runs on simulated funds against real market data. Free real-time IEX quotes at 200 req/min; $99/mo for full SIP and OPRA options.
What's missing. No filings, no disclosure, no fundamentals depth. The free feed is IEX-only, which is a thin slice of consolidated volume, so the free tier flatters the product rather than representing it.
Reach for it when the agent's job ends in an order instead of an answer.
4. Polygon (Massive) — specialist: real-time US market data
15 / 30. Tick-level US equities, options and forex with low latency, and real-time option chains included rather than tiered away.
Where it stops. Beyond market data there is nothing else: no fundamentals, no filings, no disclosure.
Reach for it when milliseconds matter more than management commentary.
5. Unusual Whales — specialist: options flow and dark pool
14 / 30. An official server over 100+ endpoints covering options flow, dark pool prints, Greek exposure, volatility and congressional trading. $50/mo is the floor, not a trial. Its flow data is unmatched here, and its congressional coverage is deliberate rather than incidental.
The barrier. There is no free tier at all, so you cannot let an agent try it before committing a card, and there is no way to size the value against your own questions first. Filings and fundamentals are out of scope.
Reach for it when you are trading positioning and need to see unusual activity as it prints.
6. Alpha Vantage — specialist: multi-asset breadth
13 / 30. The most widely integrated market-data API: equities, forex, crypto, 50+ technical indicators, long history, and options with all five greeks and open interest back to 2008. Six pricing tiers, free at 25 calls/day, real-time equities from $99.99/mo and real-time options from $199.99/mo.
The gap. No filings and no disclosure records. Live data escalates in price fast, and at 25 calls a day the free tier is a demo rather than a working allowance.
Reach for it when the agent needs FX or crypto beside equities.
7. Databento — specialist: order-book microstructure
12 / 30. The deepest raw market data here — trades, OHLCV bars, full order-book depth, real-time and historical, with OPRA options across all 17 US options exchanges. $125 signup credit, usage-based historical pricing, OPRA live from $199/mo.
The caveat. Databento's product is the data API. The MCP servers wrapping it are community projects rather than official, so tool stability and support are not vendor-backed. No fundamentals, no filings, and pricing that assumes you already know what you are buying.
Reach for it when the question involves order-book depth or venue-level prints.
8. EODHD — specialist: international coverage
11 / 30. 60+ exchanges, 150,000+ tickers, 30+ years of history across equities, ETFs, forex, crypto and macro. US options come as a marketplace add-on: end-of-day, 6,600+ underlyings from Q4 2023, with greeks and open interest. Free plan is 20 calls/day limited to the past year.
What it lacks. US disclosure data is absent, and end-of-day options rule out anything intraday. The free plan's 20 calls a day and one-year history window make evaluation slow.
Reach for it when the universe is genuinely global.
What to pair Equibles with
Four situations where you add a second connection alongside us rather than instead of us:
- Intraday options trading — our self-serve chains are 15-minute delayed. Add Polygon or Unusual Whales, or talk to us about a real-time feed if the volume justifies it.
- Tick or order-book resolution — we serve quotes, not microstructure. Add Databento.
- Placing orders — we are read-only. Add Alpaca.
- Non-US, crypto or forex — we are US-listed equities. Add EODHD or Alpha Vantage.
Notice what is missing from that list. Reading filings, following disclosure, checking fundamentals, pricing a position: we cover those, and a second server buys you nothing.
FAQ
Which one should I pick? Equibles, unless you already know you need one of the four cases above. It scores 28/30 against criteria weighted for agent research, twelve points clear of second place, and it is the only server that carries both filing text and disclosure records. It is free to start, so the evaluation costs nothing.
What is an MCP server? Model Context Protocol is an open standard for exposing tools to AI assistants. An MCP server lets a client like Claude, ChatGPT or Cursor call your data as structured tools rather than scraping a webpage.
Which of these are official servers? Equibles, Alpaca, Unusual Whales and Alpha Vantage ship vendor-maintained servers. Databento's are community-built, which matters if you need support or stable tool signatures.
Which give an agent live prices? Equibles serves real-time stock quotes on every plan including free. Option chains are 15-minute delayed on self-serve plans, with real-time available to desks and funds through sales. Polygon, Databento and Unusual Whales are live throughout. Alpaca is real-time on IEX free, full SIP at $99/mo. Alpha Vantage and EODHD gate live data behind higher tiers.
Can an agent verify a number back to its filing? Only where the server carries the document text — which on this list means Equibles. Fundamentals APIs return the value; a filings corpus lets the agent quote the sentence and cite the line. Of everything measured here, that gap decides most often whether an agent's answer can be audited.
How current is this comparison? July 2026. Pricing and coverage move quickly — check each vendor before committing.