Established onExcel, some editions: Inquire analysis and file comparisonGoogle Sheets, web: no equivalent shipped toolThird-party tools: same category of detection
Tools that examine a workbook and report on it exist, some shipped with the product and some sold separately. They are worth using and the boundary of what they can see is sharp and worth understanding first.
What ships with the product
Excel includes, in some editions, an analysis add-in that reports on a workbook's structure: the formulas it contains, the constants, the external connections, the hidden sheets, and diagrams of which cells and which workbooks depend on which. It also compares two files and reports the differences, which is the tool the entry on copies recommends.
It is not installed by default in every edition, which is why most people who have it do not know they do.
What such tools find
Inconsistent formulas. Numbers typed inside formulas. References to other files. Names that point nowhere and names nothing uses. Circular references. Cells containing error values. Formulas of unusual length or nesting depth.
That list is complete in a useful sense: for defects of structure, a tool finds them all, faster and more reliably than a person, and there is no reason to look for them by hand.
What no tool finds
Whether the model answers the question it was built for. Whether an assumption is correct. Whether the data is right. Whether a formula that is perfectly consistent is consistently wrong. Whether a lookup runs against a table with duplicate keys. Whether a figure labelled revenue is revenue.
The failure this whole site is about — the answer that is arithmetically valid and to a different question — lives entirely in that second list.
Why the boundary is where it is
A tool reads the workbook. Everything in the first list is a property of the workbook and everything in the second is a relationship between the workbook and the world, which is not in the file.
No amount of analysis closes that gap, and a report saying a model is clean means it contains no structural defects, which is a smaller claim than it sounds and is often read as a larger one.
How to use them anyway
Run the tool first and fix everything it finds, precisely so that human attention is spent on the second list. A person reading formulas to find inconsistencies is doing work a machine does better, and is not doing the work only a person can do.
The comparison feature
Comparing two versions of a workbook and getting a list of differing cells is the answer to several problems described earlier: which of the four copies is current, what changed since last month, and what somebody altered in the file you sent them.
It is the single most useful thing in this category, and it is the feature people are most surprised to learn exists.
The dependency diagram
A picture of which cells feed which, or which workbooks feed which, is useful once and then rarely, because for a model of any size it is unreadable.
The workbook-level version is the exception: a diagram of which files depend on which is a genuine organisational finding, and frequently the first time anybody has seen the whole picture.
Where third-party tools add something
Mainly in reporting: a written summary suitable for attaching to a review, and rule sets tailored to a regulated context. The detection itself is the same category of thing.
Where a workbook is subject to external scrutiny, having the report matters as much as having the findings.
What we cannot verify
The analysis add-in, its availability by edition and the comparison feature are documented by the vendor and were confirmed on a current build. We have not tested third-party products and make no claim about any of them beyond the category. Google Sheets has no equivalent shipped tool, which was established by testing.
The report is not the finding
A tool produces a list, often long, of things that are technically true and mostly harmless: an unused name, a formula longer than a threshold, an error value in a scratch cell.
Reading that list uncritically converts an audit into tidying. The useful move is to sort it by whether the item could change a number somebody acts on, and to ignore the rest deliberately rather than accidentally.
What to run before sending a model anywhere
The structural analysis, so that the recipient's first finding is not something a machine would have caught. It takes minutes and it changes how the rest of the review is received.
In short
- An analysis add-in ships with some editions and most people who have it do not know.
- For defects of structure, a tool finds them all, faster and more reliably than a person.
- No tool establishes whether an assumption is correct or the data is right.
- A tool reads the workbook, and the second list is a relationship with the world.
- Clean means no structural defects, which is a smaller claim than it is read as.
- Run the tool first so that human attention goes where only a person can look.