Fihrist Lab is the stronger fit for organic keyword verification, local vault history, complaint-led opportunity research, and multi-signal tracking.
Two browser extensions with different research depth
Fihrist Lab vs KDSpy
Both tools meet publishers in the browser, but KDSpy centers fast Kindle niche and category snapshots while Fihrist Lab connects live niche structure, keyword proof, review gaps, and long-term tracking.
Fihrist Lab is the intelligence layer Amazon KDP publishers have been missing—built to expose real demand, decode the competition, and reveal exactly where the next book can win.
Fihrist Lab suits publishers who want one connected intelligence workflow. KDSpy suits users who want a focused browser extension for Kindle niche metrics and category exports.
Fihrist Lab$19.99One-time payment
KDSpy$79 one-timeOne-time license
Last verifiedAugust 5, 2026Official sources where available
Quick verdict
The useful answer is about fit.
KDSpy may fit publishers who want its established niche snapshot, word-cloud workflow, and Kindle category export in a compact extension.
KDSpy is a focused research snapshot tool; Fihrist Lab is designed as a broader evidence and monitoring layer.
Side-by-side
Verified feature comparison
“Not publicly confirmed” means the capability or policy was not clearly documented in the official sources reviewed.
| Factor | Fihrist Lab | KDSpy |
|---|---|---|
| Price | $19.99 | $79 |
| Payment model | One-time license | One-time license |
| Refund policy | See Fihrist Lab refund policy | 60-day money-back guarantee |
| Niche research | Niche Ledger + Niche Analyzer | Kindle niche and trend research |
| Search-demand estimation | Modeled monthly range | Not publicly confirmed |
| Competition analysis | Organic, sponsored, format, category, and market-shaping books | Sales, revenue, BSR, reviews, and word-cloud metrics |
| Organic keyword verification | Yes — page-one checks excluding sponsored placements | Not publicly confirmed |
| Amazon autocomplete research | Yes — book-focused long-tail phrases | Not publicly confirmed |
| Review-gap analysis | Yes — Opportunity Gap | No dedicated complaint-mining feature publicly confirmed |
| Category analysis | Yes — category mapping and rank positions | Kindle, paperback, and hardcover category analysis |
| BSR tracking | Yes — with estimated sales, revenue, price, and category movement | Research metrics shown; continuous tracker not publicly confirmed |
| Price and promotion detection | Yes — shopper-visible price and promotion awareness | Not publicly confirmed |
| Trademark-risk research | Yes — USPTO-based research aid; not legal advice | Not publicly confirmed |
| Local data storage | Yes — research is stored in extension storage | Not publicly confirmed |
| CSV export | Yes | Spreadsheet/category export |
| Supported marketplaces | Amazon US, UK, Germany, and France | Not publicly confirmed |
| Browser integration | Chrome extension used while browsing Amazon | Browser extension for PC and Mac |
| Intended audience | KDP publishers researching niches, keywords, competitors, and tracked books | Kindle publishers seeking quick niche and category research |
Practical differences
What changes in a real publishing workflow?
Niche intelligence
KDSpy is optimized for quick niche reconnaissance using sales, revenue, BSR, reviews, and trend indicators. Fihrist Lab goes further into the anatomy of a live result page by separating paid and organic evidence and recording formats and market-shaping books.
Keyword research
KDSpy advertises a word cloud for extracting repeated listing language. Fihrist Lab discovers long-tail phrases from Amazon autocomplete and then uses Keyword Spy to verify organic page-one placement for a chosen book.
Competition analysis
KDSpy summarizes a market in a compact data view. Fihrist Lab's advantage is evidence linkage: the niche, the specific organic competitors, their reader complaints, categories, and later BSR movement remain connected.
Search-demand estimation
KDSpy's current public page does not clearly document a monthly search-demand estimate. Fihrist Lab provides an explicitly modeled monthly range and labels it as an estimate.
Review and opportunity analysis
Review counts are part of KDSpy's competitive data. Fihrist Lab additionally analyzes meaningful recurring complaints through Opportunity Gap rather than treating review count alone as the opportunity signal.
Tracking and monitoring
KDSpy's public materials emphasize research at scan time. Fihrist Lab's Tracker retains chronological changes in BSR, estimated sales, shopper price, revenue, and categories.
Pricing
Both avoid subscriptions. Fihrist Lab is $19.99 one-time and KDSpy is advertised at $79 one-time.
Workflow and ease of use
Both operate in a browser environment, which keeps research close to Amazon. Fihrist Lab offers a larger connected toolset; KDSpy's narrower surface can be faster for a simple niche check.
Privacy and local data
Fihrist Lab documents browser-local research storage. Equivalent local-storage treatment is not publicly confirmed for KDSpy.
Best use cases
Choose KDSpy for rapid category and niche snapshots. Choose Fihrist Lab when you intend to save evidence, test organic keywords, mine complaints, and revisit tracked movement.
Inside Fihrist Lab
A connected evidence system—not ten disconnected numbers.
Niche Ledger
X-rays a niche to identify meaningful competitors, sponsored listings, format distribution, categories, and market-shaping books.
Niche Analyzer
Models credible monthly Amazon search demand as a range, making uncertainty visible instead of presenting a misleading exact number.
Keyword Lab + Keyword Spy
Discovers book-focused long-tail phrases through Amazon autocomplete, then verifies organic page-one rankings while excluding sponsored placements.
Opportunity Gap
Finds meaningful recurring complaints in competing books and turns those weaknesses into practical opportunities for a better book.
Category Analyzer
Maps categories and ranking positions associated with books and niches, preserving the context needed to judge category fit.
The Tracker
Monitors chronological BSR, estimated sales, shopper-visible price, estimated revenue, and category movement over time.
Promo-Aware Pricing
Detects the price shoppers can currently see so temporary promotions do not silently distort estimates.
The Vault
Saves research locally for later comparison and CSV export without sending the research history to a Fihrist server.
Trademark™ Check
Screens title phrases with USPTO results and publishing-risk signals. It is a research aid only—not legal advice, legal clearance, or a substitute for an attorney.
Cost of access
Pricing without distorted savings math
One payment. No subscription.
- One year
- $19.99
- Three years
- $19.99
One-time license
- One year
- $79
- Three years
- $79
The official site advertises unlimited use and updates with no monthly fee.
Decision guide
Who should choose each tool?
Choose Fihrist Lab if…
- You want one extension spanning niches, keywords, reviews, categories, tracking, trademark screening, and exports
- You need organic page-one verification
- You want research saved locally
- You want a $19.99 one-time price
Choose KDSpy if…
- You prefer KDSpy's focused niche-snapshot interface
- A word-cloud view is central to your keyword ideation
- You want its established category export workflow
Questions publishers ask
Fihrist Lab vs KDSpy FAQ
01Is Fihrist Lab a good KDSpy alternative?
It can be, especially for publishers who want research inside Amazon, local research storage, and a $19.99 one-time license. KDSpy may still be the better fit when its specialist workflow matches the job more closely.
02Which tool is better for KDP niche research?
Fihrist Lab is built for live, listing-level niche inspection: it separates sponsored from organic evidence, models demand as a range, and connects competitors, categories, reviews, and tracking. KDSpy should be considered on the strength of its verified specialty described on this page.
03Does Fihrist Lab require a subscription?
No. Fihrist Lab costs $19.99 as a one-time payment for lifetime access to the current extension license, subject to its Terms of Service.
04Can Fihrist Lab estimate Amazon search demand?
Yes. Niche Analyzer produces a modeled monthly range from observable Amazon signals. It is an estimate from Fihrist Lab's model, not Amazon-reported search volume.
05Does Fihrist Lab verify organic keyword rankings?
Yes. Keyword Spy checks whether a competing book appears organically on page one for a phrase and excludes sponsored placements from that verification.
06Can Fihrist Lab and KDSpy be used together?
Yes. They do not need to be mutually exclusive. A publisher can use KDSpy for its strongest specialist workflow and Fihrist Lab for browser-based market inspection, review gaps, organic verification, and local tracking.
07Does KDSpy charge monthly?
No. Its official site lists a $79 one-time payment with no recurring monthly fee as of the verification date.
Evidence before effort