Slack file upload failing or throwing an error?
Compress your PDF instantly using the tool below — fixes both standard upload errors and Slack API size limits.
🔒 Files never leave your device⚡ Instant processing in browser💸 100% free — no signup
📄
Drop your PDF here to fix upload errors
or click to select file — PDF only
Target size (optional)
or leave blank to compress as much as possible
⚡ File Size Limits (Quick Fix)
•Slack allows file uploads up to 1GB per file for all users.
•For API-driven or user-facing file inputs in Slack integrations, the effective limit is 10MB per file.
•Free Slack workspaces have 5GB total storage per workspace. When storage is full, new uploads will fail.
👉 Fix: Compress your file below the required limit using the tool above.
About this tool
Slack upload failures can be caused by exceeding the 1GB standard limit, the 10MB API limit, or workspace storage being full (5GB on free plans). Compress your PDF here to rule out file size as the cause.
How to use this tool
Select or drag and drop your file into the tool above.
Adjust the settings or target size as needed for your specific requirement.
Wait a moment while your file is processed directly in your browser.
Download the final file safely to your device.
💡 Good to know
→Slack allows file uploads up to 1GB per file for all users.Slack Help ↗
→For API-driven or user-facing file inputs in Slack integrations, the effective limit is 10MB per file.Slack Help ↗
→Free Slack workspaces have 5GB total storage per workspace. When storage is full, new uploads will fail.Slack Help ↗
→Files must include the correct file extension when uploading via the Slack API for proper display and handling.Slack Help ↗
The most common causes are: file exceeds 1GB (standard upload), file exceeds 10MB (API integration), or the workspace has hit its 5GB free storage limit. Compress your PDF to rule out file size as the cause.Source: Slack Help ↗
What are the causes of Slack upload errors?+
File too large (over 1GB for UI uploads, over 10MB for API uploads), workspace storage full (free plan: 5GB), missing file extension in API uploads, or network issues.Source: Slack Help ↗
How do I fix a Slack upload failed error?+
First, compress your PDF to reduce file size. If the error persists, check whether your workspace has hit its storage limit (free plan: 5GB). For API uploads, ensure the file extension is included.Source: Slack Help ↗
Does Slack have a storage limit?+
Free workspaces have 5GB total storage per workspace. When this is full, uploads will fail. Paid plans (Pro, Business+, Enterprise Grid) offer unlimited storage.Source: Slack Help ↗
Why does my Slack bot reject files over 10MB?+
Slack API integrations and user-facing file inputs enforce a 10MB limit, separate from the 1GB standard upload limit. Compress your file below 10MB before sending it via the API.Source: Slack Help ↗
🔒 Files stay on device·🆓 Free forever·📵 No signup required