kumo
Kumo is a lightweight AWS service emulator written in Go that runs as a single binary or Docker container. It supports 81 AWS services and is designed for local development and CI/CD testing without requiring authentication.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | sivchari/kumo |
| Owner | sivchari |
| Primary language | Go |
| License | MIT — OSI-approved |
| Stars | 1.4k |
| Forks | 87 |
| Open issues | 179 |
| Latest release | v0.25.3 (2026-06-18) |
| Last updated | 2026-06-18 |
| Source | https://github.com/sivchari/kumo |
What kumo is
A Go-based AWS service mock that emulates 81 services across compute, storage, messaging, and other AWS domains via a local endpoint (port 4566). It provides optional data persistence, AWS SDK v2 compatibility, and minimal resource overhead suitable for CI pipelines and local workflows.
Get the kumo source
Clone the repository and explore it locally.
git clone https://github.com/sivchari/kumo.gitcd kumo# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Verify service coverage: 81 services are supported, but confirm that the specific AWS APIs your application uses are implemented and behave as expected.
- Endpoint configuration required: Applications must be explicitly pointed to http://localhost:4566 and use mock credentials (no validation enforced).
- Data persistence is optional: Use KUMO_DATA_DIR environment variable to survive container restarts; otherwise, state is ephemeral between runs.
- Single binary distribution: Easy deployment, but verify Go runtime compatibility and binary size (~50–150 MB typical) for your CI/CD platform.
- No IAM/authentication validation: Permissions and secrets are not enforced; tests cannot validate access control logic.
When to avoid it — and what to weigh
- Production Workloads — Kumo is a mock/emulator, not a production-grade service. It does not handle real data, security, or compliance requirements. Use actual AWS for production.
- Behavioral Parity Requirements — If your tests require exact AWS behavior (edge cases, error conditions, performance characteristics), emulation may not suffice. Verify service coverage before committing test suites.
- Closed-Source or Restrictive Environments — While MIT-licensed and permissive, deploying a third-party emulator may require security review or approval in highly regulated organizations.
- Multi-Region or Cross-Account Scenarios — Kumo emulates a single region/account. Distributed multi-region or cross-account testing cannot be reliably simulated with this tool alone.
License & commercial use
Licensed under MIT (MIT License), a permissive OSI-approved license. Grants rights to use, modify, and distribute, with minimal restrictions.
MIT license permits commercial use, modification, and distribution, provided the license and copyright notice are retained. No commercial restrictions or proprietary fees apply. However, as a third-party tool, organizations should confirm internal policy allows deployment in commercial projects. Kumo itself is unmaintained commercial support; verify maintenance status before relying on it in production-critical workflows.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Adequate |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Good |
| Assessment confidence | High |
Kumo is a mock—it does not enforce authentication, authorization, or encryption. No secrets are protected; data is not encrypted at rest or in transit. Not suitable for testing security-sensitive logic (e.g., IAM policies, KMS encryption). Use in isolated, non-production environments only. Verify that mock usage does not mask real security issues in application code.
Alternatives to consider
LocalStack
Larger, more mature AWS emulator with more services and advanced features (e.g., Lambda execution, advanced mocking). Heavier resource footprint; paid Pro tier for advanced features.
moto (Python)
Python-based AWS mocking library integrated into test suites. Lightweight and fine-grained; requires Python and inline test configuration. Less suitable for standalone local servers.
AWS SAM Local
AWS-native tool for local Lambda and API Gateway development. Tightly integrated with CloudFormation/SAM templates. Limited to serverless services; not a general AWS emulator.
Build on kumo with DEV.co software developers
Integrate Kumo into your development workflow or CI/CD pipeline. Download the binary, spin up Docker, or review the GitHub repository. Confirm service coverage for your use case before adoption.
Talk to DEV.coRelated on DEV.co
Explore the category and the services that help you build with it.
kumo FAQ
Can Kumo run in CI/CD pipelines?
Does Kumo persist data between restarts?
Which AWS services are supported?
Is Kumo production-ready?
Software development & web development with DEV.co
From first prototype to production, DEV.co delivers software development services around tools like kumo. Our software development agency staffs experienced software developers and web developers for custom software development, web development, integrations, and ongoing support across open-source testing and beyond.
Ready to Emulate AWS Locally?
Integrate Kumo into your development workflow or CI/CD pipeline. Download the binary, spin up Docker, or review the GitHub repository. Confirm service coverage for your use case before adoption.