Developer Tools · head to head
ESLint vs Unit21
Unit21
Cybersecurity
No-code fraud and AML risk operations platform for fintechs and neobanks
- From
- On request
- Free plan
- No
The short version
- Only ESLint has a free tier, so it costs nothing to try first.
- Each has a real cost: ESLint slow performance on large codebases compared to newer tools like Oxlint and Biome; Unit21 it is built for fintech scale rather than card issuer scale, so organisations reaching very high transaction volumes generally re-evaluate against heavier platforms and face a migration.
- Prices and features above were last checked on 1 September 2026.
Where they differ
Only the attributes on which ESLint and Unit21 actually diverge.
Identical on both: user rating (Not yet rated).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in ESLint
Nothing recorded that Unit21 does not also cover.
Only in Unit21
- No-code rule builder
- Case management
- SAR filing
- Backtesting
- Identity and device signals
- Data ingestion API
What people use each for
The jobs each tool is most often brought in to do.
ESLint
- Statically analysing JavaScript and JSX to find problems before runtimenot Unit21
- Automatically fixing issues with syntax-aware rewritesnot Unit21
- Enforcing a consistent code style across a teamnot Unit21
- Running as a CI step to block non-conforming codenot Unit21
- Writing custom rules for project-specific conventionsnot Unit21
Unit21
- A neobank whose sponsor bank requires a documented monitoring programme before it will keep the BIN sponsorshipnot ESLint
- A crypto exchange needing SAR filing and case management without building an internal compliance engineering teamnot ESLint
- A payments startup where the fraud lead needs to ship a new rule the same day a new attack pattern appearsnot ESLint
- A lender consolidating fraud alerts from three point tools into one investigator queue with a single audit trailnot ESLint
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
ESLint
- Slow performance on large codebases compared to newer tools like Oxlint and Biome
- Complexity in configuration from scratch, particularly for TypeScript support
- Limited built-in TypeScript support, requiring separate parsers and coordination with new TypeScript features
Unit21
- It is built for fintech scale rather than card issuer scale, so organisations reaching very high transaction volumes generally re-evaluate against heavier platforms and face a migration.
- No-code rule authoring shifts power to the risk team, which is the point, but without governance it produces rule sprawl that nobody can explain to an examiner two years later.
- Detection quality depends on the signals you feed it, so a thin integration produces thin results and the platform cannot compensate with proprietary consortium data the way larger vendors do.
- Pricing is quoted by volume with an annual commitment, so a fintech whose growth stalls pays for headroom it did not use.
- SAR filing coverage is oriented to United States FinCEN reporting, so firms filing in the United Kingdom, European Union or Asia handle those submissions outside the tool.
Pricing, plan by plan
ESLint
FreeNo published plan breakdown. See the ESLint review.
Unit21
On request- Unit21 Platform$undefined/year
- Priced by monitored volume and modules, annual contract
- Fraud, AML and case management packaged separately
- Implementation and historical data backfill quoted with the subscription
Which should you pick?
Choose ESLint if
- You want to start without paying.
- You work on Browser-based JavaScript, Node.js, Any JavaScript environment.
Questions people ask
- Is ESLint or Unit21 better?
- Neither clearly leads. ESLint starts at Free and Unit21 at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, ESLint or Unit21?
- ESLint has a free tier; the other does not. Paid plans start at Free for ESLint and On request for Unit21.
- Does ESLint or Unit21 run on more platforms?
- ESLint runs on Browser-based JavaScript, Node.js, Any JavaScript environment. Unit21 runs on Web.
- Can I use ESLint for free?
- Yes. ESLint has a free tier, so you can try it without paying. Unit21 starts at On request.
- What is ESLint best used for?
- ESLint is most often used for statically analysing javascript and jsx to find problems before runtime, automatically fixing issues with syntax-aware rewrites, enforcing a consistent code style across a team, running as a ci step to block non-conforming code. Of those, statically analysing javascript and jsx to find problems before runtime and automatically fixing issues with syntax-aware rewrites are not what Unit21 is typically brought in for.
- What can ESLint do that Unit21 cannot?
- Unit21 covers No-code rule builder, Case management, SAR filing, Backtesting.
Answered from the vendors’ own pages
ESLint: Does ESLint automatically fix code issues?
Many problems ESLint finds can be automatically fixed via the --fix flag. ESLint fixes are syntax-aware so you won't experience errors introduced by traditional find-and-replace algorithms.
SourceUnit21: Do we need engineers to run it?
Only for the initial data integration. After that the design intent is that risk and compliance staff author and deploy rules themselves.
ESLint: How much does ESLint cost?
ESLint is completely free and open-source software maintained by the OpenJS Foundation. The project accepts voluntary donations from sponsors.
SourceUnit21: Does it file SARs?
Yes, it generates and electronically files suspicious activity reports to FinCEN. Non-US regimes are not covered to the same depth.
ESLint: Can I write custom ESLint rules?
Yes. You can develop custom rules that work alongside built-in functionality through ESLint's plugin system, allowing complete customization for your project needs.
SourceUnit21: Can we test a rule before it goes live?
Yes. Backtesting against historical data to see projected alert volume is one of the more useful parts of the product, because alert volume is the real cost.
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- Unit21 vs IDnow
- Unit21 vs Kaspersky Total Security
- Unit21 vs LogicManager
- Unit21 vs Mullvad VPN
- Unit21 vs Private Internet Access