Amazon S3
AWS's object storage service for storing and retrieving any amount of data via API, with multiple storage tiers.
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Amazon S3 is AWS's object storage: you put files (objects) into buckets and read them back by key over an HTTP API. Apps use it for user uploads, static assets, backups and logs, and many other storage services copy its API.
Each general purpose bucket lives in one AWS Region you choose; objects stay there unless you copy or replicate them, and in most storage classes they are stored across at least three Availability Zones. Reads after a write or delete are strongly consistent. Access is governed by IAM and bucket policies, and new buckets are private, with Block Public Access on and ACLs disabled. You call it through the AWS SDKs (JavaScript, Python, Go, Java, .NET, PHP, Ruby, Rust, Swift and others) or the CLI, and give browsers presigned URLs for direct uploads and downloads.
For a small team, the useful parts are storage classes from Standard to Glacier archive tiers, plus Intelligent-Tiering, with lifecycle rules that move or expire objects automatically; versioning and Object Lock to undo or prevent overwrites and deletions; event notifications to Lambda, SQS or SNS when objects change; and replication to other Regions. It runs only in AWS's cloud.
The main cost is the AWS surface itself: IAM, policies and billing by request and transfer take time to learn. The built-in static website endpoint serves plain HTTP, so HTTPS or a custom domain means putting CloudFront in front.
Where it fits
Who uses it
No maker's live product on record yet, and 175 open-source projects that declare it in their code.
Declared in code 175How evidence is collected →
We haven't found a maker's live product that uses Amazon S3 yet — only the open-source projects below, which declare it in their code.
Open source: a project that declares Amazon S3 as a dependency in its public code — verifiable, but not necessarily a live product.
Loved and watch-outs
Themes that recur in makers' words and Hacker News comments, each linked to what it summarises.
Most loved
- Its API has become the standard that many other storage tools and self-hosted servers implement. HNHN 2HN 3HN 4
- Data is stored redundantly across separate datacenters, and AWS uses formal methods to check S3's correctness. HNHN 2
- It keeps adding primitives like conditional writes and automatic request scaling that other tools build on. HNHN 2
Watch-outs
- Storage costs far more than cheap servers or S3-compatible alternatives, and a missing VPC endpoint can cause surprise bills. HNHN 2HN 3
- Serving files straight from S3 ties you and your customers to AWS, which worries those avoiding US jurisdiction. HNHN 2
- Regional incidents reach it too: bucket creation depends on us-east-1, and some data in one damaged region was unrecoverable. HNHN 2
Alternatives to Amazon S3
All alternatives by situation →
Cloudflare R2
UploadThing
Vercel Blob
Supabase
Uppy
MinIO
SeaweedFS
GarageQuestions makers ask about Amazon S3
Where is my data stored?
In the AWS Region you pick when creating the bucket. Most storage classes spread objects across at least three Availability Zones in that Region; One Zone-IA keeps them in a single zone. source ↗
Is there an uptime SLA?
Yes. The S3 SLA pays service credits if monthly uptime falls below the commitment; S3 Standard is designed for 99.99% availability, and the infrequent-access classes for less. source ↗
Are new buckets public?
No. Buckets and objects are private by default, Block Public Access is turned on at the bucket level, and ACLs are disabled so access is managed only through policies. source ↗
Can I host a static site on S3 with HTTPS?
Not from the S3 website endpoint alone, which does not support HTTPS. AWS's answer is to serve the bucket through CloudFront, or through Amplify Hosting. source ↗
How long can a presigned upload or download URL stay valid?
Up to seven days when signed with an IAM user's credentials. If it was signed with temporary credentials, such as an IAM role, it stops working when that session expires, whatever expiry you set. source ↗
Can I store health data (HIPAA) in S3?
S3 is on AWS's list of HIPAA-eligible services, but you must sign a business associate agreement with AWS before using it for protected health information. source ↗
Do I pay egress if I move all my data off AWS?
Eligible customers can get free data transfer out when leaving AWS entirely, but only after contacting AWS Support for pre-approval; approved moves receive a temporary credit. source ↗
Is Amazon S3 free?
No permanent free tier; paid use starts at Pay as you go. source ↗
Is Amazon S3 open source or self-hostable?
Not open source, and hosted only.
Can AI coding agents work with Amazon S3?
Lovable set it up natively.
Who uses Amazon S3?
No maker's live product we track yet; 175 open-source projects declare it in their code. source ↗