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WorkWingman — Stock Market Data Sources (Plain Language)

WorkWingman looks up stock prices in two places: when it helps you weigh an equity-comp offer (how much are those stock grants actually worth?), and when it looks at how a company's stock moved around news events (layoffs, earnings) to give you context. Neither of these needs minute-by-minute prices — just today's price and a history of daily closing prices going back a few years. This doc explains why we had to switch data sources, what we looked at, and what we picked.

Why we had to switch

WorkWingman used a free source called Stooq for stock prices. Stooq recently started blocking automated requests with a "prove you're a real browser" puzzle (a bot-challenge) before it'll hand over any data. That kind of puzzle is designed to be solved by a web browser with a person sitting in front of it — not by a background service. WorkWingman will not try to trick or brute-force its way past that puzzle. That would mean pretending to be something we're not, and it could break at any time anyway since the other side controls the puzzle. So we went looking for a real, above-board replacement.

The rule we followed

We only considered data sources that officially publish a documented way for a program to ask for stock data — not sources you have to scrape or trick your way into. If a popular option turned out to be "technically works, but nobody actually gave permission for that," we say so plainly instead of quietly using it anyway.

What we looked at

We checked eight different services that offer stock price data for free (before you have to pay ), plus government filing sources, plus whether any completely-free-no-signup option exists. Here's the short version of what we found:

  • Financial Modeling Prep — free plan, needs a sign-up key, gives you 250 lookups a day and about 5 years of daily price history. Covers both "what's the price today" and "show me the history" from one place.
  • Twelve Data — free plan, needs a key, about 800 lookups a day. Good option, but reads its free-plan rules carefully before displaying that data to a user (which is exactly what we'd be doing).
  • Finnhub — free plan, needs a key, and is very generous on how often you can ask for today's price. But it turns out Finnhub quietly moved "show me the price history" behind its paid plans — so on its own, it can't do the history-lookback job we need.
  • Tiingo — free plan, needs a key, and offers the deepest history of anyone we checked (30+ years). The catch: Tiingo's free-plan rules say the data is for your own personal use only, not for showing to other people through an app — worth a closer legal look before we lean on it as the main source.
  • Marketstack — free plan is capped at only 100 lookups a month, which is too little to be useful.
  • Polygon.io — respected service, but its free plan is the most restrictive of the bunch on both how often you can ask and how far back the history goes.
  • Alpha Vantage — this is what WorkWingman already defaults to elsewhere: solid history depth, but only 25 lookups a day, which runs out fast.
  • Yahoo Finance's price-chart web address — lots of hobby projects use this, and it doesn't need a sign-up key at all. But here's the catch: Yahoo shut down its official stock API back in 2017. What people use today is an address nobody at Yahoo ever promised to keep working — it's not documented, not supported, and can be blocked or CAPTCHA-gated overnight, exactly like what just happened with Stooq. We're deliberately not using it, for the same reason we won't fight Stooq's puzzle: it's not really an invitation to use it.
  • Government filing data (SEC) — free, no key needed, totally official — but it has company financial filings, not day-to-day stock prices. Different kind of data, doesn't solve this problem.
  • Is there any free option that needs zero sign-up at all? Honestly, no. Every legitimate, above-board option requires you to register for a free key. The only "no key needed" options left are the unofficial-scraping kind we already ruled out.

What we're recommending

Default: Financial Modeling Prep's free plan.

It's the only option that comfortably does both jobs — today's price and multi-year history — from one place, with enough daily lookups (250) that WorkWingman won't run out partway through a normal day of reviewing saved jobs. It plugs into WorkWingman the same way other optional, free-by-default services already do: turned on automatically, using a free sign-up key you can get in a couple of minutes, with no cost unless we ever need to upgrade.

If that ever falls through, in order of preference:

  1. Twelve Data — strong generous free plan, good backup.
  2. Alpha Vantage — already wired into WorkWingman elsewhere; keep it as backup even though its daily limit is tight.
  3. Tiingo — best history and rate limits, but needs a legal read of its "personal use only" wording before we'd promote it above the others.
  4. Polygon.io — fine, but the most limited free plan of the bunch.

We are not using: Finnhub (can't fetch price history for free anymore), Yahoo's unofficial chart address (same "puzzle could appear overnight" risk that just took Stooq offline), or any scraping-based option. None of these meet the "documented, official, permission-given" bar we set for ourselves.

What this means going forward

Whoever wires this in should treat the chosen source the same way WorkWingman treats its other optional paid/free integrations: on by default, using a free key stored as a setting, degrading gracefully (not crashing) if that key is missing. The full technical version of this document spells out the exact web addresses and data shapes for whoever picks this up next.