Backblaze B2

Plan snapshot

Backblaze B2

FREEPAY

Free storage / trial

First 10 GB of B2 storage is free.

Separate limits

Beyond the free storage, B2 bills per stored byte-hour; downloads are free up to the included egress policy and then metered.

Billing trigger

Free for very small buckets; pay-as-you-go when storage or egress exceeds included allowances.

Best fit

Low-cost backup buckets and native B2 workflows with predictable object-storage pricing.

Cost hygiene:Keep test buckets under 10 GB and pair B2 with lifecycle rules for old versions.

Checked 2026-05-13: Backblaze B2 pricing

Backblaze B2 is a cost-effective object storage platform. AeroFTP ships two presets and lets you pick the one that matches your workload:

Preset	Backend	Best for
Backblaze B2 (native)	B2 v4 API directly	Large-file workflows, server-side copy, version history
Backblaze B2 (S3-compat)	S3 endpoint exposed by B2	Mixed-S3 estates, scripted tooling that already speaks S3

If you are starting fresh, pick the native preset. It speaks the same wire protocol as Backblaze's own tools, gets the full version history surface, and avoids the per-bucket S3 endpoint guessing that has tripped users up in the past.

Backblaze B2 (native, v4 API)

The native preset bypasses the S3 compatibility layer entirely.

What you get

• Native B2 large-file workflow (b2_start_large_file / b2_upload_part / b2_finish_large_file).
• Server-side copy via b2_copy_file - no download / re-upload round-trip.
• File version history surfaced through list_versions / download_version / restore_version so deleted or overwritten objects can be recovered from the AeroFTP UI.
• Endpoint discovery: b2_authorize_account returns the apiUrl and downloadUrl for your account, so you do not need to know the regional S3 hostname in advance.

Setup

1. Open the Backblaze App Keys page and create a new application key.
2. In AeroFTP, pick Backblaze B2 (native) in Discover.
3. Enter:
   • Application Key ID (starts with 003...)
   • Application Key (only shown at creation - copy it now)
   • Bucket Name (case-sensitive, exact match)
4. Connect. AeroFTP will run b2_authorize_account and discover the right apiUrl / downloadUrl for your account automatically.

Connection settings

Field	Value
Application Key ID	From Backblaze App Keys
Application Key	From Backblaze App Keys (one-time display)
Bucket	Exact bucket name
Endpoint	Discovered automatically by b2_authorize_account

Backblaze B2 (S3-compat, legacy)

The S3-compat preset routes B2 through the standard S3 API. It is the right choice when:

• You already have automation scripted against the S3 SDK.
• You operate a mixed estate of B2 and other S3 services and want one code path.
• You explicitly need an S3 multipart workflow rather than the native B2 large-file workflow.

Setup

1. Open AeroFTP and pick Backblaze B2 (S3-compat) in Discover.
2. Enter:
   • Key ID (starts with 003...)
   • Application Key
   • Bucket Name
   • Endpoint - copy it from the Bucket Settings page in the Backblaze console (e.g. s3.eu-central-003.backblazeb2.com). Do not prefix with https://.
3. Connect and save the profile.

Recommended defaults

• Path-style addressing: enabled (B2 does not yet support virtual-hosted style for arbitrary buckets).
• Region: auto (placeholder; B2 ignores it).

Common issues

Problem	Cause	Solution
Signature error (S3-compat)	Wrong endpoint or secret key	Verify the exact S3 endpoint in Bucket Settings and the application key
Access denied	Application key permissions too narrow	Ensure the key can access the target bucket (read + write + listAllBucketNames as needed)
Bucket not found	Wrong bucket name	The bucket name is case-sensitive
b2_authorize_account 401 (native)	Application Key ID + Key mismatch	Generate a fresh application key; the old one may have been revoked

Why two presets?

Backblaze's S3-compat layer is excellent but it does not surface every B2 feature. The native preset wins on:

• Server-side copy (b2_copy_file) - the S3-compat endpoint emulates CopyObject but rewrites the file rather than reusing the source bytes for cross-bucket copies.
• Version history - b2_list_file_versions returns the full version chain; the S3-compat layer hides this behind versioning headers.
• Large-file workflow - native b2_finish_large_file is the original B2 behaviour and avoids the S3-compat multipart commit edge cases that have caused intermittent issues for some users.

The S3-compat preset wins on:

• Tooling reuse - any S3 SDK / CLI works as-is.
• Cross-provider scripting - the same code path that talks to AWS / R2 / Wasabi / MinIO also talks to B2.

You can have both presets installed at once and switch per-profile.

Related

• S3-Compatible Storage
• Provider Reference