Almost every AI code review tool prices one of two ways: per seat, or per usage. Both are legitimate. But they behave very differently as your team grows, and the wrong choice quietly turns a useful tool into a line item people start questioning. This post explains how each model works, where each one wins, and how to estimate what your team would actually pay.
How per-seat pricing works
You pay a fixed amount per developer per month, usually with a minimum seat count. Every developer who might open a pull request needs a seat, because the tool refuses to review PRs from unlicensed authors.
Where it wins: predictable invoices, and a good deal for teams where everyone opens many PRs every week.
Where it hurts:
- Headcount, not usage, drives cost. The contractor who opens two PRs a month costs the same as the engineer who opens forty.
- Seat management becomes a chore. Someone has to add and remove seats as people join, leave, or move teams. Forget to remove one and you pay for it for months.
- Occasional contributors get excluded. Teams avoid buying seats for designers, data scientists, or open-source contributors, so their PRs go unreviewed. Those are often exactly the PRs that need a second pair of eyes.
- Model choice is hidden. The vendor picks the model and absorbs the cost, so you cannot trade cost for depth on a specific repository.
How credit-based pricing works
You prepay a monthly balance. Each review debits the balance by what it cost, based on the size of the diff and the model used. Anyone in the organisation can open a PR; there is no per-person licence.
Where it wins:
- Cost tracks value. A quiet month costs less. A big refactor week costs more, and you can see exactly why.
- No seat administration. Add the GitHub App to a repository and every contributor is covered.
- Full transparency. Each review's cost is visible, so you can tune which repositories review on every commit and which review only when a PR opens.
- Model choice is yours. Spend more on the payments service, less on the docs repo.
Where it hurts:
- Less predictable in the abstract. If you have never measured your PR volume, the first month is a guess. Most tools solve this with a hard cap: when the balance reaches zero, reviews pause rather than overspend.
- Someone has to top up. A forgotten balance means paused reviews. Good tools email admins before that happens.
A worked comparison
Take a team of 12 developers opening about 160 pull requests a month, with a typical diff of a few hundred changed lines.
| Model | What you pay | Notes |
|---|---|---|
| Per seat at $15 to $30 per developer | $180 to $360 per month | Same price whether they open 160 PRs or 40 |
| Credits, GPT-4.1-class model | A few cents per review, so roughly $5 to $15 in usage | A $30 monthly plan covers it with credit left over |
| Credits, premium reasoning model on critical repos only | Usage rises on those repos, the rest stays cheap | You decide where depth is worth paying for |
The per-seat figures are typical ranges across the market, not a specific vendor's price. The point is the shape: per-seat cost scales with people, credit cost scales with reviews. For most teams under 50 engineers, reviews are far cheaper than people.
Questions to ask any vendor
- What happens when I exceed my plan? Overage billing, throttling, or a hard pause? A hard pause is the only one that guarantees no surprise invoice.
- Do unused credits or seats carry over? Seats never do. Credits sometimes do. Carry-over is the difference between a plan and a subscription tax.
- Can I see the cost of a single review? If the answer is no, you cannot manage the spend.
- Can I bring my own model key? If you already have an OpenAI or Anthropic account with negotiated rates, a bring-your-own-key option can be the cheapest path of all.
- Are there limits on repositories or contributors? Some "unlimited" plans cap repositories instead of seats.
How DiffNova prices
DiffNova uses credits, not seats. Each monthly plan grants its full price as review credit ($20, $30, or $50), unused credit carries over, and reviews pause at zero. Top-ups start at $5. Every review's cost appears in the PR summary comment and in the billing ledger. If you already have an OpenAI or Claude key, the bring-your-own-key plan is $5 per month with full features and your provider bills the usage directly.
There is no limit on repositories or contributors on any plan, because the thing you are paying for is the review, not the person who asked for it.
Try it on a real repository with the free 7-day trial at diffnova.com, then look at the ledger after a week. That number is your real monthly cost.