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Semver Range Linter for npm Packages
A focused CLI and CI tool that lints package.json dependency ranges for common semver footguns, with special attention to 0.0.x caret behavior, peer dependency ranges, and transitive version conflicts. It suggests corrected ranges and can auto-fix them across monorepo workspace packages in a single command.
Why this matters
You publish npm packages from a monorepo and one day a consumer reports a build break because your caret range on a 0.0.x dependency did not actually admit the latest patch version. You discover that 18 workspace packages each pin slightly different ranges of the same transitive dependency, and some use caret syntax that silently fails to pick up new patches. There is no linter that caught this — you had to learn the semver 0.0.x quirk the hard way and now must manually audit every package.json across your workspace.
- · Built for npm package authors and monorepo maintainers who want to prevent dependency range mistakes before they affect consumers.
- · Most likely monetization: Freemium with paid CI integration and monorepo batch-fix features.
The Pain · Narrative
You publish npm packages from a monorepo and one day a consumer reports a build break because your caret range on a 0.0.x dependency did not actually admit the latest patch version. You discover that 18 workspace packages each pin slightly different ranges of the same transitive dependency, and some use caret syntax that silently fails to pick up new patches. There is no linter that caught this — you had to learn the semver 0.0.x quirk the hard way and now must manually audit every package.json across your workspace.
Score Breakdown
Market Signal
Go-to-Market
Indie and small-team npm package maintainers who publish from monorepos with 5+ workspace packages
~20K monorepo maintainers on npm who publish regularly
npm registry organic discovery with a catchy package name and strong README
$9/month for CI integration and batch-fix, CLI free forever
2,000 weekly npm downloads of the free CLI within 30 days, 30 paid CI users
MVP Scope · 1–2 weeks
- Implement core semver range analysis logic covering 0.0.x caret, tilde, and exact pin detection
- Build a CLI that scans a single package.json and reports all problematic ranges with suggested fixes
- Add monorepo workspace detection that scans all package.json files in a workspace
- Create an auto-fix mode that applies suggested range corrections in place
- Write unit tests covering the known 0.0.x edge cases from the discussion
- Wrap the CLI as a GitHub Action with inputs for auto-fix-on-push and fail-on-severity
- Add a --diff mode that shows proposed changes in a PR-friendly format
- Build a simple landing page with an interactive demo pasting a package.json
- Publish to npm with a memorable name and comprehensive README
- Submit to developer newsletters and communities for initial feedback
Differentiation
Why This Might Fail
Self-rebuttal — the most important trust signal
- 1The problem is narrow and well-understood by experienced developers who may view it as a one-time learning rather than a recurring need requiring tooling.
- 2Existing tools like eslint-plugin-package-json or npm-package-json-lint could add the same rules quickly, eliminating the need for a standalone product.
- 3Free CLI distribution may attract users but fail to convert to paid CI plans if the batch-fix feature is perceived as a minor convenience rather than a necessity.
Evidence Summary
How AI synthesized this insight — no verbatim quotes
Two commenters in this discussion specifically called out that caret ranges on 0.0.x versions do not admit the next patch under semver rules, requiring explicit ranges like >=0.0.57 <0.1.0. This is a recurring footgun that affects package maintainers who use caret syntax assuming patch-level compatibility. The need to update ranges across 18 workspace packages manually further indicates a gap in automated range management tooling for monorepos.
Action Plan
Validate this opportunity before writing code
Recommended Next Step
Validate
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Landing Page Copy Kit
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Headline
Semver Range Linter for npm Packages
Sub-headline
A focused CLI and CI tool that lints package.json dependency ranges for common semver footguns, with special attention to 0.0.x caret behavior, peer dependency ranges, and transitive version conflicts. It suggests corrected ranges and can auto-fix them across monorepo workspace packages in a single command.
Who It's For
For npm package authors and monorepo maintainers who want to prevent dependency range mistakes before they affect consumers
Feature List
✓ Detects 0.0.x caret ranges that will not admit next patch and suggests explicit ranges ✓ Flags inconsistent transitive dependency pins across monorepo workspace packages ✓ Auto-fix mode that updates all affected packages in one command ✓ Peer dependency range validator that checks declared peer ranges match actual usage ✓ CI integration as GitHub Action with configurable severity thresholds
Where to Validate
Share your landing page in r/GitHub · CopilotKit/CopilotKit — that's exactly where these pain points were discovered.
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