An S3 client that lives next to your databases.
Mongrel is a desktop S3 client for Amazon S3 and S3-compatible stores. Browse prefixes as folders, drag files between local and remote panes, copy a presigned GET URL, and keep secret keys in the OS keychain — in the same app as FTP, FTPS, SFTP, terminals, and 30+ database engines.
Windows x64 and ARM64 · macOS Apple silicon · Linux x86-64
// Connections → File Transfer → S3
Point at Amazon S3 or a compatible endpoint.
Provider presets fill Amazon S3 (blank endpoint) or DigitalOcean Spaces (https://region.digitaloceanspaces.com, TLS required). Custom / other is for MinIO, Cloudflare R2, Backblaze B2, and Wasabi. Test Connection lists the bucket or prefix once, then Save. File Manager / is the optional path prefix.
// What ships
Object storage with a real file manager.
Amazon S3 without a custom host
Leave the endpoint blank. Mongrel uses the SDK regional resolver, including us-east-1 on s3.us-east-1.amazonaws.com, and signs SigV4 with the bucket region.
S3-compatible stores
DigitalOcean Spaces, MinIO, Cloudflare R2, Backblaze B2, and Wasabi use a service HTTPS URL. Spaces locks TLS on and prefers virtual-hosted Auto.
The same File Manager
S3 is a File Transfer profile. Dual panes, Name/Size sort, a non-selectable .. row, remembered local folders, and the Transfers drawer match FTP/FTPS.
Prefixes as folders
Listings treat common prefixes as directories. New Folder writes a prefix/ marker. Folder delete removes every key under that prefix. Recursive transfers stop at 100000 objects.
Presigned GET URLs
Right-click a file and copy a time-limited GET URL. Amazon URLs use the regional virtual-hosted host. Spaces uses bucket.region.digitaloceanspaces.com unless you force path-style.
Secrets stay in the keychain
Secret access keys and optional STS session tokens never land on the profile, in Connection Sync, or in export. Access key IDs and bucket names are ordinary profile fields.
// Limits
What this S3 client does not pretend to be.
Mongrel is not a bucket-policy editor, CloudFront console, or Azure Blob / GCS client. There is no folder synchronization script and no POSIX chmod on objects. Use it when you need an S3-compatible File Manager beside SSH, SQL, and Kubernetes — not as a replacement for the AWS console.
// FAQ
Frequently asked questions.
Is Mongrel an S3 client?
Yes. Connections → New Connection → File Transfer → S3 creates a standalone S3 profile. Connect or Open File Manager to browse a bucket in the same dual-pane File Manager used for FTP and FTPS.
Which S3-compatible services work?
Amazon S3 with a blank endpoint, DigitalOcean Spaces, MinIO, Cloudflare R2, Backblaze B2, and Wasabi. Paste the S3 API host, not a CloudFront, website, or CDN URL.
Does Mongrel support path-style and virtual-hosted addressing?
Yes. Auto uses virtual-hosted style for Amazon S3 and Spaces, and path-style for other custom endpoints. Buckets whose names contain a dot always use path-style under Auto so TLS wildcards still match.
What IAM actions does a listing need?
s3:ListBucket on the bucket and prefix. Downloads and presigned URLs need s3:GetObject. Uploads, new folders, rename, and delete need s3:PutObject and s3:DeleteObject.
Can I chmod or resume an S3 transfer?
No. Objects have no POSIX chmod, resume, or symlink. Rename is copy-then-delete. Cancel removes any partial destination. Pause and resume exist only for SFTP when the server supports random access.
Are downloads locked without a license?
No. Listings, downloads, and presigned URLs stay available. Open, Test, uploads, and remote mutations require an active license or trial, and honor read-only profiles.
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