What happens if you use PUT and POST requests multiple times?

PUT and POST are HTTP methods with different semantic meanings:

• POST is usually used to create a new resource. It is not idempotent — repeated requests can create multiple resources or have different effects.
• PUT is used to replace or create a resource at a specific URI. It is idempotent — repeated requests with the same data lead to the same result.

If you perform multiple POST requests with the same data, it is likely that multiple resources will be created (for example, multiple records in a database).

If you perform multiple PUT requests with the same data at the same URI, the resource will be overwritten, but the final state will remain the same.

Thus:

• Multiple POSTs can lead to duplication or accumulation of data.
• Multiple PUTs lead to a stable state of the resource without accumulating changes.

This is important to consider when designing APIs and client logic to avoid unwanted effects.