Best content optimization tools: five tested, no winner
Five products, one frozen keyword fixture, one ground truth rebuilt from the live Google (us) top 10. Not one of the content scores told us where a page would rank. The furthest any full run landed from zero was ρ −0.115, which is no answer at all. So this page names no winner. What it can do is say what each product did on each thing we measured: how much of its term list the ranking pages actually share, how close the competitor set it shows you is to the real top 10, what it costs, and how much of a generated draft we could trace to a source. Pick on the measurement that matches your job.
Every figure here is read at build time out of the run that produced it. One exception: the Clearscope row. That run recorded no price, so the tier came off the vendor’s own billing page, and the cell carries the date we read it. Where a run did not measure something the cell is empty. How each column is measured is set out in our methodology.
What each one did
| Tool | Score ↔ rank (ρ) | Term precision@30 | SERP overlap | Cheapest paid plan | Claims sourced | Run |
|---|---|---|---|---|---|---|
| Fraseno term list | −0.115 | 0.120 | 60.8% | $39/mo | 75% | 20 keywordskeywords-v12026-08-18 |
| Clearscopepilot, n = 3 | — | 0.201 | — | $129/mobilling page, 2026-08-20 | — | 3 keywordskeywords-v1 ids 1-32026-08-20 |
| NeuronWriter | −0.052 | 0.230 | 86.2% | $23/mo | — | 20 keywordskeywords-v12026-08-21 |
| Scalenut | −0.071 | 0.158 | 87.2% | — | — | 8 keywordskeywords-v1 ids 1–82026-08-21 |
| Surfer SEO | −0.102 | 0.161 | 84.6% | — | — | 20 keywordskeywords-v12026-08-24 |
← swipe the table sideways for the rest of the columns
No total row and no overall score. Adding a correlation to a price and a precision figure needs weights, and any weights would be ours rather than something we measured.
These runs cover different slices of the same frozen fixture, captured between 2026-08-18 and 2026-08-24. Each row states its own keyword count and its own fixture, and no figure is averaged across rows. Where two tools did measure the same thing, the head-to-head pages put them side by side and say which rows rest on the same keywords.
Clearscope’s free trial allows 3 reports and all 3 were spent, so every Clearscope measurement on this page rests on three keywords: its term precision, and anything scored against a set of pages. Its price is not a measurement. The $129 a month in its row was read off the billing page on 2026-08-20, and the sample size has nothing to do with it. At that size one keyword moves a mean further than the distance between most of the other rows, so the pilot never sets a high or a low here and is never the answer to a “which one” question below. A full run replaces it. Read the Clearscope pilot.
ρ is the mean Spearman correlation between a tool’s content score and its page’s real Google position. Positive means higher-scoring pages ranked higher. We call a score predictive at |ρ| 0.3 and above; below that it carries no rank information whichever side of zero it sits on. Term precision@30 is how much of a tool’s top 30 suggestions turns out to be vocabulary the ranking pages share. SERP overlap is the share of domains its own top 10 has in common with the real Google (us) top 10. Claims sourced is how much of a generated draft we could trace back to something. A dash means that run did not measure it, which is not the same as a zero.
Which one for which job
Every sentence here points at a figure we measured. Most sit in the table above; where one does not, the sentence links to the page it sits on. Where the table has a dash, this section has nothing to say.
You want a term list at all. NeuronWriter, Scalenut and Surfer SEO hand you terms to work into the draft. Frase does not, so the precision figure in that row scores the nearest thing on offer, a keyword research panel. Read it as a different question rather than a bad answer. Clearscope hands you one too, though everything we measured about it came off a trial quota (pilot, n = 3).
You want the list to match what the ranking pages share. NeuronWriter’s top 30 scored 0.230 against our answer key, the highest of the three full runs that publish one, on 20 keywords. That is about 23% of the list it hands you. The rest is still yours to judge: every row, keyword by keyword. Read the ordering as dated, too. We put the same keywords through these tools a day apart and the term lists had already moved: what changed by the next morning.
You want the competitor table to look like the real SERP. Three of the runs crawled a top 10 sharing 84.6% to 87.2% of its domains with Google’s. Frase sits apart at 60.8%: more of the pages it puts in front of you are not the ones you are up against.
Price is the constraint. Two of the four full runs recorded a price, in dollars a month, cheapest first: NeuronWriter $23, Frase $39. Each was read on the day that tool was run, so it is as current as the row it sits in. Scalenut and Surfer SEO show a dash because those runs did not record pricing. A dash is not free. Clearscope is not in that order. Its trial run (pilot, n = 3) spent nothing, so the $129 a month in its row is the cheapest paid tier, read off the billing page on 2026-08-20 rather than measured.
You want the generated draft to hold up. Only Frase has been through that test. In the Frase drafts, 75% of the claims we pulled traced to a source. The other four have no figure, so this page cannot say whether their drafts hold up better or worse.
You want the score to tell you where you will land. None of them does. Every score we have run against the real top 10 came out flat, and the products that agree on nothing else agree on that. If the number a tool asks you to optimise toward is the reason you are buying it, our tests give you nothing to go on: what we measured, and on what.
What holds beyond one row
Two kinds of page sit behind this table. Cite those, not this one.
Measured across the tools
Each takes one measurement and reads it across every tool that produced it.
- Does content score predict Google rank? — No content score we have tested predicts where a page ranks on Google.
- How accurate are content tool term suggestions? — How much of what these tools tell you to write about is a term the ranking pages share.
- Do content scores change on their own? — Whether the terms and the score a tool gives you today are the ones it gives you tomorrow.
Measured on the search results
These score the Google pages themselves, not any tool’s output, so nothing in the table above is being judged by them. They come out of the same crawl the runs were scored against.
- Do longer pages rank higher on Google? — Page length told us nothing about rank in our sample.
- How many organic results are left in Google's top 10? — The top tens we measured were not ten places a written page could win.
The runs behind this page
- Frase review — A research-to-draft pipeline with no term list, and a content score that did not predict Google rank in our sample. Tested 2026-08-18
- Clearscope review — The widest term coverage we have measured, under letter grades that did not track even its own SERP. Three-keyword pilot; full run pending. Tested 2026-08-20 · pilot
- NeuronWriter review — A weighted term list and a SERP that tracks Google's closely, under a content score that did not predict rank in our sample. Tested 2026-08-21
- Scalenut review — A weighted term list and a scored competitor table, under a content score that did not track rank against Google or against its own SERP. Eight-keyword run. Tested 2026-08-21
- Surfer SEO review — A full 20-keyword run: its content score did not track Google rank under either URL match, and a day-two re-run swapped terms on three of five keywords while the scores held still. Tested 2026-08-24
Two at a time
The comparison matrix holds the same rows with the footnotes each one needs. A pair page exists wherever both runs measured at least one thing in common.
- Clearscope vs Surfer SEO Tested 2026-08-20 / 2026-08-24
- Frase vs NeuronWriter Tested 2026-08-18 / 2026-08-21
- Frase vs Scalenut Tested 2026-08-18 / 2026-08-21
- Frase vs Surfer SEO Tested 2026-08-18 / 2026-08-24
- NeuronWriter vs Scalenut Tested 2026-08-21 / 2026-08-21
- NeuronWriter vs Surfer SEO Tested 2026-08-21 / 2026-08-24
- Scalenut vs Surfer SEO Tested 2026-08-21 / 2026-08-24
What this page will not tell you
There is no overall score here and no ranked list. To rank these products we would have to decide how much a correlation is worth against a dollar and against a precision figure, and that decision would be ours, not a measurement. We already publish the finding that a single content score carries no rank information. Building a sixth score out of the other five would repeat the mistake one level up.
The rows are ordered by run date. Every “highest” above names the column it is highest in, and none of them is a verdict on the product. A tool can top the term column and still be the wrong purchase, because what these numbers do not cover is the editor, the brief and the writing.
Coverage is thin on purpose. Each row costs a full run, and we publish a row when the numbers exist. Want a specific tool moved up the queue? hello@toolverdict.ai.
Pages carrying affiliate links say so at the top. A commission cannot move a test result: the keyword fixture is frozen, the runs are scripted, and we keep the raw responses. More on who we are and how we make money.