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validator

A Go library that checks whether structs and fields hold valid data, using tags on struct fields.

GitHub Download v10.30.5
Stars
20.2k
Forks
1.5k
Licence
MIT
Language
Go
Last update
7 days ago
Type
Library

What it is

validator is a Go package that checks data against rules you write as tags on struct fields, such as required, email, or minimum and maximum values. It can also compare fields with each other and validate items inside slices, arrays, and maps. It is the default validator used by the gin web framework, according to the README.

  • Validate a registration struct so that email, password length, and required fields are checked in one call
  • Check that an end date is later than a start date using cross-field tags such as gtfield
  • Validate every element of a slice or every key and value of a map with dive
  • Return translated error messages for users by using the translations example in the repo

Great for

  • Go developers validating request bodies or form data in web APIs
  • Teams that want validation rules declared next to struct definitions
  • Projects needing cross-field checks, such as a confirm-password field matching a password field
  • Developers who need translated or customized error messages

Not ideal for

  • Non-programmers, since it is a code library rather than an app (it requires writing Go code)
  • Projects not written in Go, because it is a Go package
  • Users who need validation rules loaded from a database or UI without code changes; the README describes tag-based rules in code
Step-by-step guide: how to use validatorInstall, first run, examples, tips and FAQs
validator alternatives

How to get it

  1. 1

    Install with a package manager

    You'll need: Go (version not stated in the provided README)

    Install the package

    go get github.com/go-playground/validator/v10
  2. 2

    Run it

    • Install the package with go get as shown above
    • Import github.com/go-playground/validator/v10 in your Go code
    • Add validation tags to your struct fields
    • Create a validator with validator.New(validator.WithRequiredStructEnabled()) as the README recommends
    • Call validate.Struct on your value and check the returned error
  3. 3

    Get the most out of it

    • Use WithRequiredStructEnabled when creating the validator, as the README recommends for new users
    • Use the struct-level, custom field types, and translations examples in the _examples folder
    • Use alias tags to group several validations under one tag name
    • Use the field name extraction feature to report JSON names in errors

Downloads

Source code (.zip)master branch · straight from GitHubRelease v10.30.5Release notes and source

Strengths

  • Rules are declared as readable tags next to the struct fields
  • Many built-in checks are listed in the README across strings, network addresses, and formats
  • Returns errors in a consistent form that can be inspected with errors.As

Trade-offs

  • The README says the default behaviour of WithRequiredStructEnabled will change in v11, so new users are advised to opt in now
  • Documentation is pointed to pkg.go.dev and the README is partly truncated, so some details must be checked there

How it compares

ProjectStarsTypeLevelUpdatedBest for
validator (this)20.2kLibraryintermediate7 days agoGo developers validating request bodies or form data in web APIs
pydantic29.3kLibrarybeginner4 days agoPython developers who already use type hints and want runtime checks on incoming data
validator.js23.7kLibrarybeginner2 months agoJavaScript developers validating form or API input on Node.js
effect17.5kLibraryadvanced4 days agoTeams building large or long-lived TypeScript back-end services
class-validator11.9kLibrarybeginner8 months agoTypeScript developers validating request bodies or form data in Node.js or the browser
react-hook-form44.9kLibraryintermediate5 days agoReact developers building forms with several fields

Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.