Market Data API Guide

Stock Market Data APIs Compared: Verified Pricing, Rate Limits & Real Per-Call Math

Last verified: August 9, 2026 · Every number below was checked against the vendor's live pricing page on that date. Where we could not verify a number, we say so instead of guessing.
Affiliate disclosure: This page contains affiliate links to EODHD (each one individually labeled "affiliate link"). If you subscribe through one, we earn a commission at no extra cost to you. No other vendor on this page has any relationship with us, and no vendor paid for placement or review — rankings are based on the published specs and pricing shown below, and were written before any affiliate relationship existed.

Head-to-head: EODHD vs Alpha Vantage — which stock API is actually cheaper? Verified pricing, cost-per-call math and a use-case winner table.

Free tool: Market data API cost calculator — enter your symbols and refresh rate, see which plans your volume breaks.

On this page:
1. The 30-second answer · 2. Full comparison matrix · 3. Cost-per-call math · 4. Which API fits your use case · 5. Vendor profiles · 6. Methodology
Also in this guide: Best free stock market data APIs — real limits tested

1. The 30-second answer

Prototyping / learning: Twelve Data's free tier (8 credits/min, real-time US data) or Finnhub's free tier (60 calls/min) beat Alpha Vantage's free tier (25 calls/day) by a wide margin.

Cheap deep history: EODHD (affiliate link) at $19.99/mo for 30+ years of end-of-day data across world markets and 100,000 calls/day is the strongest price-per-history deal we measured.

Serious intraday/tick work: Massive (formerly Polygon.io) — unlimited API calls from $29/mo, trade-level data at $79/mo.

High request volume on a budget: Alpha Vantage premium starts at $49.99/mo for 75 req/min with no daily cap — but its free tier is now the most restrictive of the group.

2. Full comparison matrix

All prices are monthly, verified August 9, 2026. "n/v" = not verified — the vendor's page didn't state it clearly or was unreachable, and we won't guess.

VendorFree tierCheapest paidRate limit (paid entry)History depthReal-time?Notable
Alpha Vantage25 calls/day$49.9975 req/min, no daily cap20+ yrs EODYes (US)Simple REST, huge indicator library
Massive (ex-Polygon.io)5 calls/min, EOD only, 2 yrs$29 (Starter)Unlimited calls5 yrs @ $29 · 10 yrs @ $79 · 20+ yrs @ $19915-min delayed until $199 tierTrade-level data at $79; rebranded from Polygon.io in 2026
Twelve Data8 credits/min (800/day), real-time US$29 (Grow)55 credits/minDecades OHLCVYes (US on free!)Credit system — heavier endpoints cost more credits
EODHD20 calls/day, 1 yr range$19.99100k calls/day, 1000 req/min30+ yrs, world marketsWebSockets only on $99.99 tierSplits/dividends/adjusted included at entry tier
Finnhub60 calls/minn/v (quote-based)n/vn/vYes (US on free)Generous free real-time tier; paid pricing not published plainly

3. Cost-per-call math (the part nobody publishes)

Sticker prices mislead because vendors meter differently — per minute, per day, or per "credit." Here is the effective monthly ceiling and cost per 1,000 calls if you ran each entry-level paid plan flat out:

PlanPrice/moMeteringMax calls/month (theoretical)Cost per 1k calls at ceiling
Alpha Vantage $49.99$49.9975/min~3.24M~$0.015
Massive Starter$29UnlimitedUnbounded→ $0
Twelve Data Grow$2955 credits/min~2.38M credits~$0.012/1k credits*
EODHD All World$19.99100k/day~3.0M~$0.0066

*Twelve Data credits ≠ calls: fundamental endpoints can cost 10–100 credits each, so real per-call cost depends heavily on your endpoint mix. This is the single most common billing surprise reported with credit-metered APIs.

Two practical readings of this table:

If you poll continuously (dashboards, scanners), Massive's unlimited metering is structurally different from everyone else — you can't out-poll your plan. If you batch daily (EOD portfolio jobs, backtest refreshes), EODHD's 100k/day at $19.99 is the cheapest verified path, and its 30-year history means one vendor covers both your live and backtest data.

4. Which API fits your use case

You are building…Best verified fitWhyAvoid
A hobby project / learningTwelve Data free or Finnhub freeReal-time US data at $0; enough rate for one userAlpha Vantage free (25/day exhausts in minutes)
A backtesting engineEODHD $19.99–$29.9930+ yrs adjusted EOD + splits/dividends at entry priceMassive Starter (only 5 yrs history at $29)
A live scanner / dashboardMassive $29–$79Unlimited calls; minute+second aggregatesPer-day metered plans — you'll hit the cap mid-session
A production trading systemMassive $199 (real-time + trades)Real-time quotes, 20+ yrs, financials includedFree tiers of anything (terms typically bar commercial use)
Global multi-market coverageEODHD or Twelve Data Pro ($99)World EOD ($19.99) vs 70+ real-time markets ($99)US-only-focused plans
Fundamentals research at scaleEODHD Fundamentals $59.99Fundamentals + insider data, 100k calls/dayCredit-metered fundamentals (cost blowup)

5. Vendor profiles

Alpha Vantage — the incumbent with a shrinking free lunch

Alpha Vantage remains the API most tutorials teach, and its endpoint simplicity is real: one GET request, JSON out, 100+ technical indicators server-side. But the free tier is now 25 requests per day — enough to demo, not enough to build. Premium is honest and flat: $49.99/mo buys 75 req/min with no daily limit and no overage fees, scaling linearly to $249.99 for 1,200 req/min. Annual plans effectively give two months free. It's a fair mid-tier choice when you want predictable metering and broad indicator coverage without managing your own TA library.

Massive (formerly Polygon.io) — the structural outlier

Polygon.io rebranded to Massive (polygon.io now 301-redirects to massive.com) — many older comparison articles miss this. The pricing model is the outlier in this group: every paid tier has unlimited API calls, and you pay instead for data depth and freshness. $29 buys 5 years + 15-min delayed minute/second bars; $79 adds trade-level data and 10 years; real-time quotes require the $199 Advanced tier, which also bundles financials & ratios (sold separately at $29). If your workload is chatty, this is the only vendor here where the meter simply isn't running.

Twelve Data — best free tier, watch the credit math

The free tier is the most usable in this comparison: real-time US equities, forex and crypto at 8 credits/min (800/day). Grow at $29 unlocks 20+ markets and EOD global data at 55 credits/min; Pro at $99 brings 70+ markets, real-time EU stocks and 500 WebSocket credits. The caveat is the credit system: a price quote is 1 credit, but heavier endpoints multiply, so budget against your actual endpoint mix, not the headline number. Annual billing discounts about 17%.

EODHD — the value pick for history and breadth

Links in this section are affiliate links (eodhd.com) — see disclosure above.

$19.99/mo buys 30+ years of end-of-day data for effectively all world markets, with splits, dividends, and adjusted prices, metered at a generous 100,000 calls/day. Intraday adds $10/mo; full fundamentals is $59.99; the $99.99 all-in-one adds WebSockets, news and options. Two flags: the free tier (20 calls/day, 1 year of range) is trial-sized, and the personal-use plans exclude commercial use — production products need their enterprise pricing.

Finnhub — great free tier, opaque paid tier

Finnhub's free tier (60 calls/min with real-time US data) is arguably the most generous entry point in the market. But as of our August 2026 check, its paid pricing is not plainly published on a public page — plans are effectively quote-based per dataset. We don't list numbers we couldn't verify; if you need Finnhub's premium data, get a written quote and compare it against the per-call math in section 3.

6. Methodology

We verify every price and limit against the vendor's live public pricing page and record the verification date at the top of the page. Numbers we cannot verify are marked "n/v" rather than estimated. Theoretical call ceilings are computed as rate_limit × minutes_in_month (43,200) or daily_cap × 30, whichever the vendor's metering implies. We re-verify monthly or when a reader reports a change. No vendor saw this page before publication.