Both Platform UI usage in v1 (as reported in EZP-27271), and direct REST usage in any version of eZ Platform is currently limited by having to encode files as base64 and upload as part of the REST payload on content API calls.

This means both the client (browsers) and server is not able to handle large files:

• Browsers are limited to around 500mb
• Server can not use builtin file uploading features & needs to place this in PHP memory at least twice (during decoding)
  • In effect end users needs to raise PHP's memory_limit setting which is meant to only be about app memory usage, not upload size. On PHP 7.x with Platform UI (1.13.4-dev) we have measured that you need around memory_limit: 200M to upload 50mb file, around 150mb used by uploaded file, and 50mb left for application execution (which can vary).

So as REST consumer there is a need for a better way to upload files. Designed in a way which PHP is able to handle, and so we can even tackle support for tracking upload progress.