Ajv is a highly performant JSON Schema validator written in JavaScript. It supports JSON Schema drafts 04, 06, 07, 2019-09 and 2020-12, offering comprehensive validation capabilities. Ajv prioritizes speed and efficiency, making it suitable for applications requiring robust and rapid schema validation. It includes features like custom keywords, formats, and error messages, enabling tailored validation solutions. Ajv boasts broad adoption within the JavaScript ecosystem, indicating its reliability and practicality.