JSON
Definition.
JSON: JavaScript Object Notation, an open standard file format and data interchange format that uses human-readable text to store and transmit data objects.
In More Detail
JSON won as the data format for APIs because it maps cleanly onto the structures every language already has, and it is readable without tooling when you are debugging a response.
Its gaps are worth knowing. There is no date type, so timestamps travel as strings and both sides have to agree on the format — ISO 8601 in UTC avoids most timezone bugs. There is also no comment syntax, which is why configuration files in JSON are more annoying to maintain than they first appear.
In Practice
This is the format every REST API I build speaks — a Django REST Framework backend serializes to JSON, and a Flutter or Next.js frontend deserializes it back into typed objects on the other end.
Related Terms
Browse the full software development glossary, or see the frequently asked questions.
If you are working out whether this applies to your own project, the case studies show where it turned up in real builds, services lists what I take on, and pricing gives the starting figures.
Let's Build Something Exceptional Together
Have a project in mind? I'd love to hear about it. I usually reply within 24 hours.
< 24 hrs
Avg. response time
30+
Projects shipped
98%
Client satisfaction