How to evaluate a stock scanner: 5 questions before you pay.
Most scanner sales pages are 50 filters and a screenshot. Here are the five questions that actually predict whether a tool will be useful in six months — and how Finviz, Trade Ideas, Zacks, and Tapeline answer them.
I've signed up for almost every prosumer stock scanner since 2018. Most fail the same way: the tool is fine for a week, then you realise you have no way to tell whether the calls it surfaces are actually working. By month three you've added it to the pile of $20-$50/month subscriptions you keep forgetting to cancel.
If you're shopping for a scanner, these five questions will save you the cycle:
1. Can you see the formula?
If the answer is "we use a proprietary blend of signals" you're being sold magic. The two questions you can't answer about magic are "is this working?" and "will this still work next month?" Tipranks, Zacks, Kavout, WallStreetZen all hide theirs. Tapeline publishes the exact 6-factor weighted equation on /how-it-works.
2. Where's the public scorecard?
Newsletter shops have known for 30 years that you should hide your losers. Mark Hulbert built a career being the only neutral grader of newsletter performance because everyone else hid the data. Look for a tool that auto-publishes every call it makes against the next-day market move — not a curated highlight reel. We do this at /scorecard; almost nobody else does.
3. What does the data come from?
"AI-powered signals" usually means "we bought a feed from Polygon and slapped a score on top." Which is fine — that's also our spine. But know it. Bloomberg Terminal at $32k/yr uses similar feeds; the premium is the speed and breadth of their proprietary chat and curated news, not the raw data. Anyone charging $200/month for "exclusive AI signals" is reselling Polygon and Finnhub.
4. Is the cheapest tier real?
Test it. If the free or cheapest paid tier strips out so many features the product is unusable, the team is incentivised to upgrade-trap rather than retain. Tapeline Free is hard-capped to 20 tickers and 24-hour delayed by design — the real product, just narrower — because that's the most honest preview.
5. Can you cancel in one click?
If you have to email support to cancel, that's a tell about how the team treats you generally. Stripe-portal cancel-in-one-click is table stakes; if it's not there, leave. (Yes, ours is.)
If a tool can't answer questions 1 and 2, walk away regardless of price. They're cheap to ask and predict 80% of the future regret.
See it live.
14-day Premium trial. No credit card. The scoring formula above runs on every US ticker every minute.