Mount S3 on Mac like a local drive.
KastDrive mounts any S3-compatible bucket into Finder — AWS, Cloudflare R2, Backblaze B2, Wasabi, or MinIO — with SigV4 signing, multipart streaming for huge objects, and version history you can restore from right inside Finder. No more AWS CLI for a quick file.
Free tier: 1 S3 bucket, forever — no credit card required
Why KastDrive for S3 on macOS
The AWS Console is fine for ops and the CLI is fine for scripts, but neither is fine for browsing a bucket the way you'd browse a folder. KastDrive closes that gap — Finder-native, streaming, and version-aware.
AWS, R2, B2, Wasabi, MinIO
Drop-in presets for Amazon S3, Cloudflare R2, Backblaze B2, Wasabi, and MinIO — plus any other S3-compatible endpoint. Custom regions, paths, and virtual-host styles all supported.
SigV4 request signing
Every request is signed with AWS Signature Version 4 — the same scheme the official SDKs use — so your access keys never travel over the wire and scoped IAM roles work out of the box.
Multipart streaming
Large objects stream as multipart uploads and downloads, so a 50 GB export opens in Finder without staging the whole file in memory or on disk first. Resumable, parallel, and fast.
Version history
When bucket versioning is on, KastDrive exposes every prior object version in Finder via Get Info and lets you promote or restore any of them — no console, no CLI, no guesswork.
How it works
Three steps from access key to a Finder sidebar that streams objects on demand.
Add your bucket
Pick an S3, R2, B2, Wasabi, or MinIO preset, paste your access key and secret, and choose a bucket. SigV4 handles signing from there — keys stay on your Mac.
Mount into Finder
The bucket appears under Locations in Finder as a folder of cloud-badge placeholders. Browse millions of objects without downloading a single byte upfront.
Stream and version
Open any object to stream it via multipart download. On save, KastDrive uploads in parallel parts; if versioning is on, the previous copy is one click away in Get Info.
KastDrive vs Mountain Duck & ExpanDrive for S3
Mountain Duck and ExpanDrive both mount S3 through FUSE and force full downloads. KastDrive streams multipart on demand through File Provider, surfaces object versions in Finder, and costs less up front.
| Feature | KastDrive | Mountain Duck | ExpanDrive |
|---|---|---|---|
| Endpoints | S3, R2, B2, Wasabi, MinIO | S3 + generic | S3 + generic |
| Request signing | SigV4 | SigV4 / v2 | SigV4 |
| Multipart transfer | Yes — streaming | Limited | Limited |
| Object versioning | Yes — Finder UI | No | No |
| Online-only files | Yes — cloud badges | No — full download | No — full download |
| Finder integration | Native File Provider | Kernel extension | Kernel extension |
| Price | $0 free / $29 once | $39 + per-year renewals | $49 + per-year renewals |
Mountain Duck & ExpanDrive pricing as of June 2026. No affiliation with either vendor.
Your buckets, browsable in Finder.
Mount your first S3 bucket free. Upgrade to Pro for unlimited mounts, bandwidth scheduling, and Cryptomator vaults.