Obstor

Obstor is an open-source object storage server for teams that want S3-compatible access and SFTP under infrastructure they operate themselves. It suits operators building distributed storage around existing S3 tools; its single-server mode is intended for development and evaluation. The central trade-off is clear: broad storage and integration capabilities come with a requirement to plan for distributed deployment to use key production features.

Overview

Obstor works with S3 SDKs, command-line tools, and applications without code changes, so it can fit into established S3-oriented workflows without requiring clients to be rewritten. Its native SFTP server adds a file-transfer route, and files uploaded over SFTP are stored as S3 objects. That shared storage model is useful for teams serving both application integrations and direct file transfers.

In a distributed setup, Obstor shards and replicates objects across connected nodes, with each object stored in at least two global locations. It also supports multi-site replication, continuous replication, and failover orchestration. Those capabilities make it relevant to teams managing data across locations, but do not make standalone deployment a production shortcut: standalone servers are intended for development and evaluation.

Key features

Durability and data management

Configurable erasure-coding parity protects against drive and node failures. Object versioning and lifecycle policies support recovery and retention needs. The important constraint is that versioning, object locking, and bucket replication require distributed deployment with erasure coding. Teams that need those controls should account for that architecture from the start, rather than expect them from a standalone server.

Security and integration

Server-side encryption supports SSE-C and SSE-S3, with KMS integration. Obstor uses HMAC-SHA-256 for key derivation and AES-256-GCM or ChaCha20-Poly1305 for authenticated encryption. IAM provides users, groups, policies, and service accounts using S3 and AWS IAM policy syntax, which will be most useful to teams already working with those access-control conventions.

Event notifications can be sent to Kafka, NATS, AMQP, Redis, PostgreSQL, Elasticsearch, and webhooks. That range gives teams several ways to connect storage events to existing systems. The project describes machine learning, analytics, and application data as suitable workloads; the deployment and recovery requirements still make operator capability a key part of the fit.

Deployment choices

Obstor can be installed as a single binary, through Docker or a Kubernetes Helm chart, or built from source. Official standalone instructions cover macOS, GNU/Linux, and 64-bit Windows. The Docker Compose example creates four distributed instances and supports up to 16 Obstor services, giving teams a defined way to assemble a multi-instance environment. These options offer flexibility, but none removes the need to understand and manage the distributed setup for production-oriented features.

Pricing

The Open source plan costs nothing and is self-hosted under the Apache 2.0 license. That makes Obstor a straightforward choice for teams willing to provide their own infrastructure and operations. It is not a hosted-storage subscription: teams must run the service themselves, and the standalone configuration is limited to development and evaluation.

The free plan includes the open-source software rather than a paid tier with a published service quota or seat allowance. Its practical limits are architectural: versioning, object locking, and bucket replication require distributed deployment with erasure coding. Choose it when you can manage that deployment; look elsewhere if you need a managed service or want production data controls from a single server.

Platforms

Obstor is listed for API, Linux, macOS, self-hosted, web, and Windows use. Its documented standalone operating systems are macOS, GNU/Linux, and 64-bit Windows, while Docker and Kubernetes Helm chart provide additional deployment routes. The self-hosted approach gives operators control over placement and setup, but also places deployment and ongoing operation on them.

Who it's for

Obstor is best for infrastructure teams that want an open-source S3-compatible server, need SFTP ingestion into the same object store, and can operate distributed storage. Its encryption, IAM, notifications, and replication capabilities serve teams integrating storage into application and data workflows. It is a poor fit for someone seeking a managed storage service or a production deployment that must remain standalone.

Pros and cons

• Pro: S3 clients can work without code changes, while native SFTP stores uploads as S3 objects, accommodating two common access paths in one system.
• Pro: Distributed storage combines sharding, replication, configurable erasure coding, and support for multi-site replication and failover orchestration.
• Pro: Encryption options, IAM policy support, and a broad set of notification destinations give operators choices for security and integration.
• Con: Standalone servers are for development and evaluation, and versioning, object locking, and bucket replication require distributed deployment with erasure coding.
• Con: Self-hosting means the team must provide and operate the infrastructure rather than rely on a managed storage service.

Alternatives

For teams comparing storage replication software, browse the Storage Replication Software category. The alternatives below differ in platform, storage model, or pricing approach, so the right choice depends on the workload.

• Synology Photos is a free option with Android, iOS, desktop, web, and browser-extension platforms; choose it instead when photo storage is the need and a Synology NAS is available.
• SeaweedFS offers a free community-support plan for any cluster size, with GitHub issues and discussions, public documentation, and no guaranteed response time. Consider it instead when those community terms and its listed Linux, macOS, Windows, API, and self-hosted platforms fit the project.
• LINBIT DRBD has a free open-source community version with DRBD 9 source code, guides, and community support, as well as a LINBIT Starter plan at $1,000 a year. It is an alternative for Linux, Windows, or self-hosted storage needs when DRBD is the preferred approach.
• XtreemFS is free and open source under a BSD license; consider it when that project is a better fit for a Linux, macOS, Windows, or self-hosted deployment.
• Longhorn is free, open-source distributed block storage for Kubernetes. Choose it instead when Kubernetes block storage, rather than S3-compatible object storage, is the requirement.
• OpenEBS is a free, open-source Kubernetes storage option; consider it when that platform and storage focus better match the need.
• Amazon S3 uses usage-based billing with no minimum charge, covering storage, requests, retrieval, transfer, management, replication, and other features. It is the alternative to consider when that pay-as-you-use model is preferable to operating a self-hosted server.
• DAOS is another free option for API, Linux, and self-hosted use.

Verdict

Choose Obstor if you want an Apache 2.0-licensed, self-hosted object store that lets existing S3 clients coexist with SFTP uploads and you can run distributed infrastructure. Its strongest case is the combination of familiar access methods with replication, encryption, IAM, and event integrations. Look elsewhere if you need a managed service or production versioning, object locking, and bucket replication without a distributed deployment.