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Trust & honesty

How Kindlefish works — and what our numbers really mean.

Authors spend real money launching a book. So we're precise about where our data comes from, how our estimates are built, and exactly what we will and won't promise.

How we estimate

Kindlefish is built on real Amazon data plus a large licensed book index — not invented numbers. Every figure is blended from named sources, and every figure is labelled with its source and a confidence level:

Live Amazon SERPReal listings, prices & ranks, fetched on demand
Amazon-derived demand signalSearch-demand estimates from a 120M+ keyword corpus
Ad-bid rangesReal advertiser bid ranges from licensed Amazon advertising data
Our Amazon book index318K+ books · 150K+ categories · 1.46M keyword↔ASIN links
BSR→sales velocityA labelled estimate (crowd-calibrated), shown as a range

Search volume

We model how often a phrase is searched by combining licensed keyword-volume data with Amazon autocomplete prominence, the breadth of results a phrase returns, and the observed rank-velocity of books targeting it. The result is a monthly estimate — a grounded indicator of relative demand, not a metered count of every keystroke (no third party has that).

Competition score

We weigh how many established titles target a phrase, their review counts, their sales rank, and how entrenched the top results are. A high score means a crowded, hard-to-crack term; a low score means daylight.

Opportunity

Opportunity blends demand against difficulty — it's a derived estimatewe'd look at first, always alongside the underlying figures, never instead of them.

How fresh is it?

Live searches run against Amazon in real time; our historical index refreshes on a rolling schedule. You're diving in current water — not last year's.

What the confidence labels mean

Every datapoint carries a confidence label so you know how much weight to put on it. More corroborating signal, more confidence.

HighStrong, consistent signal across multiple sources. Safe to act on.
MediumReasonable signal, but thinner or more volatile. Sanity-check it against the competition view.
LowSparse or noisy data — often a very new or very niche term. Treat as a hint, not a verdict.

The calibration caveat

Turning an Amazon Best Sellers Rank (BSR) into a sales figure relies on a BSR → sales-velocity curve. Ours is a crowd-calibrated, US-anchored estimate that we recalibrate periodically — it is not blessed or published by Amazon, and it is less precise outside the US store and at the long tail.

So we show sales as ranges, never single numbers, and we label the confidence. Treat a sales range as a sized indicator of order-of-magnitude — not a promise of units sold.

Our honesty pledge

Estimates are indicators, never guarantees. We will never tell you a keyword will sell, or that any choice guarantees a bestseller. Publishing has too many variables — your cover, your writing, your timing, your ads. Kindlefish surfaces better-informed decisions; the book is still yours to make great.

What that means in practice:

  • Every number is labelled as an estimate, with a confidence level.
  • Fee, our AI research diver, delivers research and a publish-ready package you review and finalise — never a “done-for-you bestseller.”
  • We'd rather show you a sobering “this niche is crowded” than a flattering fiction.

Amazon & trademarks

Kindlefish is an independent tool, not affiliated with or endorsed by Amazon. Kindle, Kindle Direct Publishing (KDP), and Amazon are trademarks of Amazon.com, Inc. We are not partners, agents, or representatives of Amazon, and we don't access any private Amazon seller account data.

Kindlefish is built by authors, for authors.

Privacy (summary)

We collect only what we need to run your account and your searches. Your search history and saved keywords are tied to your account and visible only to you.

  • Manuscripts you upload to Fee are private — used to generate your report, never sold, and retained only for the limited delivery, recovery, support, and retention windows in the Privacy Policy.
  • We don't sell your personal data. Analytics are aggregate and anonymised.
  • You can export or delete your account data at any time.

This is a plain-language summary; the full Privacy Policy governs in detail.

Terms (summary)

  • Use Kindlefish for your own book research. Don't scrape, resell, or redistribute the data wholesale.
  • Estimates are provided “as is” as decision-support — you're responsible for your publishing decisions.
  • Pro is billed monthly or annually and renews until cancelled; cancel anytime from your account.
  • We may refine our estimation models over time as Amazon's ecosystem changes.

This is a plain-language summary; the full Terms of Service govern in detail.

Refund policy

Kindlefish uses strict digital-content refund terms because paid reports and Pro research access cannot be returned once used.

  • Pro: first payments may be refundable within 14 days only before paid-only use begins.
  • Fee reports: final once generation starts or the report is delivered, except for failed delivery, duplicate charges, or material technical faults we cannot fix.
  • Included Fee credits have no cash value; if a credit report fails, the normal remedy is a rerun or credit restoration.

Last updated 19 June 2026 · Full policy: Refund Policy. Questions? Open the tool or contact us.