HTTP POST requests do not have a universally defined size limit; instead, it primarily depends on the settings of the server and client.
Generally, the server typically imposes size limits to prevent large requests from wasting server resources or causing potential denial-of-service attacks (DoS).
For example, when using web servers like Apache, the default size limit for the POST request body is 2MB. However, this size can be modified through configuration files. In Apache, you can adjust the size limit by modifying the LimitRequestBody directive in the httpd.conf or .htaccess files.
For other servers like Nginx, there is a similar setting named client_max_body_size, which defaults to 1MB and can also be adjusted in the configuration files.
During development, if your application needs to accept large uploaded files or substantial data, you must ensure that the server configuration supports receiving large POST requests. Additionally, consider client-side limitations, such as browsers or client programs that may have their own size restrictions for POST requests.
Overall, the size limit for HTTP POST requests can be configured as needed, so when designing applications, you should set this value reasonably based on actual requirements.