Side-by-side comparison of the five indexing tools self-publishers and authors actually consider — Cindex, SKY Index, MACREX, PDF Index Generator, and IndexStudio. Pricing, feature matrix, and editorial verdicts to help you choose.
Updated May 2026 · Includes Cindex open-source transition · Editorial verdicts, not paid reviews
From AI-powered automation to traditional professional tools
AI-Powered Web Platform
The Professional Standard (now open source)
Windows-only Professional Suite
Side-by-side comparison of all major indexing software features
| Feature | IndexStudio | Cindex | SKY Index | MACREX | PDF Gen |
|---|---|---|---|---|---|
| AI-Powered Analysis | |||||
| Web-Based Access | |||||
| Free Tier Available | |||||
| Cross-Platform | |||||
| Offline Capability | |||||
| Learning Curve | Easy | Steep | Steep | Steep | Easy |
| Processing Time | Minutes | Hours/Days | Hours/Days | Hours/Days | Minutes |
| Best For | Self-publishers | Professionals | Professionals | Professionals | Basic needs |
Honest assessments of each tool from the IndexStudio founder. The disclosure on the first verdict applies to the whole page.
Disclosure: I built IndexStudio, so treat this section as a vendor brief, not a review. The pitch is straightforward — if you're a self-publisher who wants a real back-of-book index without buying $579 software or learning a desktop indexing tool, this is built for you. Generating and previewing the index is free, so you can decide whether the output is worth $39 before you pay. Unlock for $39 per book to download the final index. The professional tools below have decades of credibility that a 2024 product doesn't. They also have steep learning curves and price points priced for people who index for a living.
The respected veteran. Cindex has been the professional indexer's tool of choice for thirty years for a reason: the feature set is comprehensive and the data model handles cross-reference work that AI tools still struggle with. Going open source in 2024 removed the only real downside (cost). The catch is the learning curve — this is software built for full-time indexers, not authors indexing their own book over a weekend. If you're doing one book and don't intend to become an indexer, Cindex is overkill. If you're a working indexer or planning to learn the craft seriously, it's still the standard.
Powerful but Windows-locked and expensive. $579 is a real commitment for a single book, and the Windows-only requirement is disqualifying if you're on a Mac. The professional indexing community is largely split between Cindex and SKY; both produce indexes of similar quality in the hands of someone who knows what they're doing. With Cindex now free and cross-platform, SKY Index is hardest to recommend to anyone who isn't already invested in its workflow.
Long-running professional tool with a loyal user base; similar tradeoffs to SKY Index — high cost, steep learning curve, real professional capability once mastered. If you're not already a working indexer, the cost-to-value ratio is hard to justify for a one-off project. The MACREX users I've spoken to swear by it, but they also swear by it after years of investment.
The honest cheap option. $69.95 will get you a basic keyword-frequency index from a PDF — no AI, no contextual understanding, no real cross-references. It's not a substitute for a professional index or an AI-generated one, but if your bar is 'better than nothing' and your budget is tight, it delivers what it promises. The output looks more like a concordance than a back-of-book index, so check whether that's what you actually want before paying.
How this comparison was made: I went looking for an alternative to professional indexing software while writing my own book, evaluated each of these tools, and built IndexStudio because none of the existing options fit a self-publisher with a single project. The verdicts above reflect that perspective. For purely professional indexing work, Cindex remains the standard recommendation.
Generating and previewing your index is free. $39 per book to unlock and download — one-time, no subscription. Up to 1,000 pages.
No credit card to preview · $39 to unlock and download · Export as TXT, DOCX or PDF