The Azure equivalent of AWS S3 is Azure Blob Storage, per Microsoft’s comparison. Same object storage model with hot/cool/archive tiers. Azure’s Blob service supports an S3-compatible API for migration ease. The team that needs S3 API access can use Azure Blob with the S3-compatible SDK; the team that wants native Azure uses Blob’s native API.
Table of contents
- Azure Blob vs S3
- Storage tiers
- S3-compatible API
- Pricing
- Migrating from S3 to Blob
- S3 alternatives for multi-cloud
- FAQ
Azure Blob vs S3
Same conceptual model:
- Buckets (S3) = Containers (Blob).
- Objects (S3) = Blobs (Blob).
- Regions (S3) = Regions (Azure).
Naming:
- S3 bucket names: 3-63 chars, lowercase, no underscores.
- Azure container names: 3-63 chars, lowercase, letters/numbers/hyphens only.
Storage tiers
| Tier | Use case | S3 equivalent |
|---|---|---|
| Hot | Frequent access | S3 Standard |
| Cool | Infrequent (30+ days) | S3 Standard-IA |
| Cold | Rare (90+ days) | S3 Glacier Instant |
| Archive | Long-term | S3 Glacier Deep Archive |
The team that picks Cool for infrequent access saves on storage.
S3-compatible API
Azure Blob has an S3-compatible API. Configure your code:
# AWS S3 SDK with Azure Blob endpoint
import boto3
s3 = boto3.client(
's3',
endpoint_url='https://<account>.blob.core.windows.net',
aws_access_key_id='<account_name>',
aws_secret_access_key='<account_key>'
)The team that uses the S3 SDK with Azure endpoint has portable code that works on either cloud.
Pricing
| Tier | Azure per GB | S3 per GB |
|---|---|---|
| Hot | $0.0184 | $0.023 |
| Cool | $0.010 | $0.0125 |
| Archive | $0.00099 | $0.00099 |
Azure is slightly cheaper for Hot and Cool. Same for Archive.
Migrating from S3 to Blob
Tools:
- AzCopy: Microsoft’s data transfer tool. Fast bulk transfers.
- Azure Data Factory: ETL-style with transformations.
- rclone: open-source, supports S3 and Blob.
- S3-compatible API: use existing S3 tools against Blob endpoint.
The team that uses AzCopy for bulk migration has fast transfers. The team that uses the S3-compatible API has minimal code changes.
S3 alternatives for multi-cloud
If you want S3 API across clouds without Azure-specific bindings:
- Cloudflare R2: S3-compatible API, no egress fees.
- Backblaze B2: S3-compatible, cheapest storage.
- Wasabi: S3-compatible, no egress fees.
- MinIO: self-hosted S3-compatible storage.
The team that uses S3-compatible alternatives has portable apps with cloud-provider flexibility.
FAQ
What is the Azure equivalent of S3?
Azure Blob Storage. Same object storage model, different naming (containers vs buckets), slightly different API.
Can I use the AWS S3 SDK with Azure Blob?
Yes - Azure Blob has an S3-compatible API. Configure the SDK with the Azure Blob endpoint URL.
Is Azure Blob cheaper than S3?
Slightly for Hot and Cool tiers. Same for Archive. Egress costs differ - check Azure’s pricing page for current rates.
How do I migrate data from S3 to Azure Blob?
AzCopy is fastest for bulk. rclone for cross-cloud sync. The team that uses AzCopy has parallel transfers with high throughput.
What about Azure Files (SMB)?
Azure Files is the SMB file share service, not an S3 equivalent. Use Azure Files for traditional file shares, Blob Storage for object storage.
If you are sizing the infrastructure for the kind of project this post covers, the RunxBuild hosting calculator is the right place to model the line items. The compute, the memory, the storage, the bandwidth, the database - each one is a separate number, and the team’s mental model for the platform is the sum of those numbers. The RunxBuild dashboard is where the team sees the actual usage in one place.
Useful related references: