Is there any alternative ajv(json-schema validator) for deno?

You don't need an alternative, you can use ajv.

Ajv provides a bundle for browsers: https://cdnjs.cloudflare.com/ajax/libs/ajv/6.12.2/ajv.min.js

All you need to do is download it, save it to your project and add: export default Ajv at the bottom of the file.

ajv.js

/* ajv 6.12.2: Another JSON Schema Validator */
!function(e){if("object"==typeof exports&&"undefined"!=typeof module) /*....... */
//# sourceMappingURL=ajv.min.js.map

export default Ajv;

index.js

import Ajv from './ajv.js'

const ajv = new Ajv({allErrors: true});

const schema = {
  "properties": {
    "foo": { "type": "string" },
    "bar": { "type": "number", "maximum": 3 }
  }
};

function test(data) {
  const valid = validate(data);
  if (valid) console.log('Valid!');
  else console.log('Invalid: ' + ajv.errorsText(validate.errors));
}


const validate = ajv.compile(schema);

test({"foo": "abc", "bar": 2});
test({"foo": 2, "bar": 4});

Remember that Deno is a JavaScript runtime, so any code which uses plain JavaScript, you'll be able to use it with very little modification, in this case just export default Ajv

You have some options to use none-deno modules.

The easiest way is to use a service like esm.sh and import it like:

import Ajv from 'https://esm.sh/ajv@8.6.1';
import addFormats from 'https://esm.sh/ajv-formats@2.1.0';
const ajv = new Ajv({allErrors: true});
addFormats(ajv);

esm.sh even provides .d.ts definitions if available, so you can import types as well.

import Ajv, {ValidateFunction} from 'https://esm.sh/ajv@8.6.1';
const validate: ValidateFunction = new Ajv().compile(schema);

In some cases, you can even import the raw typescript file directly from git. But Ajv imports json files directly, which deno does not support atm.

Till now, ajv-like schema validator is not available for Deno. However, you can try value_schema for schema validation. It has both Node.js and Deno versions.

jtd is a viable alternative. It is a deno native implementation of JSON Type Definition, aka RFC 8927, which is an alternative to json-schema validation (and thus ajv) but has a similar purpose.