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The media library is a central store for all the images, videos, and audio files you use in your posts. Instead of re-uploading the same brand assets every time, you upload once and attach them to any post, on any channel, whenever you need them. Everything is organized in a searchable grid so your media is always a few clicks away.

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Supported file types

PostSider accepts the following media formats:
  • Images - JPEG, PNG, GIF, WebP, AVIF, BMP, and TIFF
  • Video - MP4, WebM, QuickTime, and Matroska
  • Audio - MP3, WAV, OGG, MP4 audio, and WebM audio are accepted by backend upload paths; the current dashboard picker is primarily image/video oriented

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Uploading media

You can upload files in two ways:
1

From the Media Library view

Navigate to Media Library in the dashboard sidebar. Drag and drop files directly onto the page, or click the Upload button to open a file picker. Uploaded files appear in the grid immediately.
2

From the post composer

While composing a post, click the attachment icon in the toolbar. You can upload a new file on the spot or browse your existing media library to attach a previously uploaded file.

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Reusing media across posts

Any file in your media library can be attached to multiple posts. In the composer, click Browse Library to open a media picker, search or scroll to find the file you want, and click to attach it. Reusing media doesn’t create duplicate files - PostSider references the same stored asset each time.

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Storage backends

Where your media files are physically stored depends on how your PostSider instance is configured:
  • MinIO - the bundled Docker Compose stack stores files in its MinIO volume.
  • Local filesystem - files are saved to the ./uploads/ directory on the server. This is useful for development or non-Compose deployments.
  • Cloudflare R2 - files are stored in a Cloudflare R2 bucket. Ask your admin whether R2 is enabled for your instance.
Your admin controls which storage backend is active. As a user, the media library behaves identically regardless of backend - the difference is only in where files are physically stored.

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Platform media limits

Different social platforms have different limits on how many images or videos you can attach to a single post. PostSider enforces these limits in the composer so you don’t accidentally exceed them. For platforms not listed above, refer to the composer - it will show the attachment limit for the channel you’ve selected.

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Uploading via the API and SDK

You can upload media programmatically using the public API or the official SDK. The REST API accepts the formats above; client.upload() currently maps only png, jpg, jpeg, and gif correctly. REST API
SDK
The returned id or path can then be referenced when creating a post via the API.
When building AI agent workflows with the PostSider MCP server, use the postsider_upload_media_from_url tool to import media directly from a public URL into the media library - no manual download and re-upload needed. This is especially useful when an agent generates or discovers an image online and needs to attach it to a scheduled post.