How it works
S3 stores objects in buckets, each addressed by a key, and is designed for eleven nines (99.999999999%) of durability by keeping copies across several facilities. Apps upload through presigned URLs, serve files through CloudFront, and use lifecycle rules to move older data to cheaper classes such as Standard-IA and Glacier.
Launched in 2006, it set the standard: Cloudflare R2, Backblaze B2, DigitalOcean Spaces, Supabase Storage and MinIO all offer S3-compatible APIs. Its price has several parts (storage per GB, requests per thousand, and data transfer out to the internet), and for popular public files the transfer part usually dominates.
Amazon S3 pros and cons
Pros
- Designed for very high durability, with a long track record
- Storage classes from instant access to low-cost deep archive
- Works with the whole AWS toolset, from Lambda to Athena
- The S3 API is supported by almost every tool and library
Cons
- Egress fees make serving popular files expensive
- Pricing has many parts and is hard to estimate
- Misconfigured public buckets have leaked data, though new buckets block public access by default
When to use Amazon S3
Pick it when
- Your app already runs on AWS
- Archives and backups on cheaper cold storage classes
- Data that other AWS services will process
Skip it when
- Files are downloaded heavily by the public, where R2 avoids egress fees
Amazon S3 pricing
Pay as you go
S3 Standard is about $0.023 per GB-month in US regions, plus request fees. Data out to the internet is about $0.09 per GB after 100 GB free each month (shared across AWS).
Amazon S3 pricing page (opens in a new tab)Approximate, checked September 2026.What the other tools cost
Amazon S3 vs the alternatives
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