Isomorphic-validation
Validation has never been easier.
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Isomorphic-validation is a JavaScript library that lets you write validation logic once and run it on both client and server.
- for
- JavaScript developers building forms that need shared client-server validation.
- pricing
- open source
- license
- MIT
- v0.0.102 years ago
Key features
- Single source of truth — Write validators once and reuse them on both client and server.
- Uniform API — Simple, straightforward API without many method names or config options.
- Grouping & cloning — Reuse validation steps across different forms without repetition.
- Interactivity hooks — Easily connect UI side-effects to validity states for responsive feedback.
- Any validation strategy — Supports on-focus, on-input, on-submit, or server-side validation flows.
- Functional style — Designed for developers who prefer functional programming patterns.
Use cases
- Validate a signup form on the browser and re-validate on the server with the same rules
- Create reusable field validators shared across multiple forms in a large app
- Integrate validation with i18n libraries to provide localized error messages
- Connect UI components to validation states for instant user feedback
- Teach validation concepts without juggling separate client and server solutions
Isomorphic-validation FAQ
Can I use the library on both Node.js and browsers?+
Yes, the library is isomorphic and runs in any JavaScript runtime, both client-side and server-side.
How does it handle asynchronous validation?+
Asynchronous checks are abstracted away, letting you write linear-looking code while the library manages the async flow.
Is there support for custom validation strategies?+
You can implement any strategy such as on-focus, on-input, on-submit, or full server-side validation.
Does it work with internationalization?+
The library can be used together with i18n libraries to provide localized error messages.
What programming style does it favor?+
It follows a functional programming style, suitable for developers who prefer functions over classes.
Summarized by DevHunt from itihon.github.io · Oct 5, 2026. Details may change; check the official site.
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