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Wilma

Free plan Self-hostedWeb

What Wilma is

Wilma is a free, self-hosted tool for developing and testing applications that rely on other services. It combines an HTTP/HTTPS transparent proxy with a service stub: it can capture, decode, save, and forward traffic, including two-way SSL, or return configured responses. It runs as a proxy, a stub, or in a mixed mode. Stub behavior is set in JSON files, which can be changed or uploaded through the UI or service while Wilma is running. Interceptors can inspect or alter requests and responses in real time; users can add their own interceptors, condition checkers, and response formatters, including by uploading classes or JAR files. Wilma Message Search finds logged request-response pairs. The project describes use in unit, integration, functional, end-to-end, performance, and manual testing. Under heavy load, Wilma can suspend decoding and then disk logging, restoring these operations as load returns to normal. Old logs can be deleted on a configurable schedule, and logging can be toggled in the UI. It is GPLv3 or later software with no warranty. Deployments are available as Docker images, release ZIP files, or builds from source. Wilma requires JRE 11; Message Search requires JDK 11.

Who it suits

Wilma suits developers and testers who need to simulate dependent services or inspect HTTP/HTTPS traffic in test environments. It supports self-hosted deployment and offers Java and .NET service libraries.

What it does well

Runs as a proxy, stub, or mixed mode.
Stub settings can change while Wilma is running.
Custom interceptors and response formatters are supported.
Docker images and release ZIP files are available.

What to know first

Wilma requires JRE 11.
Message Search requires JDK 11.
The license states there is no warranty.

Plans

Plan	Billed and limits	Price
Wilma	GPLv3.0 licensed software	Free

As epam.github.io lists them, read 30 Sept 2026. The maker's own page has the final word.

Getting started

Open the Wilma website.
Choose a Docker Hub image, a GitHub release ZIP, or build from source.
Install JRE 11 for the Wilma application.
Install JDK 11 if you will use Wilma Message Search.
Configure stub behavior with JSON files, then use the UI or service to adjust it while running.

Verdict

Wilma combines traffic proxying, service stubbing, and message inspection for development and testing. Teams should plan for its Java runtime requirements and GPLv3-or-later license.

Questions

What does Wilma cost?

The listed Wilma plan is free. Wilma is GPL version 3 or later software.

Which platforms does Wilma support?

Wilma is listed for self-hosted and web use. Deployment options include Docker Hub images, GitHub release ZIP files, and builds from source.

What Java versions does it require?

Wilma requires JRE 11. Wilma Message Search requires JDK 11.

Can Wilma handle HTTPS traffic?

Yes. It supports HTTP/HTTPS transparent proxying, including two-way SSL. The repository notes TLS 1.1, 1.2, and 1.3 support for version 2.0, with possible extra configuration.

Can I add custom behavior?

Yes. Users can add message interceptors, condition checkers, and response formatters, including by uploading classes or JAR files.

Facts from Wilma's own pages

Deployment: The maker offers Docker images, prepared GitHub release ZIP files, or building a release from source. · epam.github.io, 30 Sept 2026
Distribution: The applications are available as Docker Hub images, GitHub release ZIP files, or builds created from source. · epam.github.io, 30 Sept 2026
Extensibility: Users can add custom condition checkers, response formatters, and message interceptors, including by uploading classes or JAR files. · epam.github.io, 30 Sept 2026
Headquarters: Newtown, Pennsylvania, United States · epam.github.io, 28 Sept 2026
Integrations: Wilma provides a Java service library through Maven Central and a .NET service library through NuGet. · epam.github.io, 30 Sept 2026
License: The repository states Wilma is free software under the GNU General Public License version 3 or later, with no warranty. · github.com, 30 Sept 2026
Load behavior: When load rises, Wilma can disable message decoding and then disk logging, and it restores those operations as load returns to normal. · epam.github.io, 30 Sept 2026
Load safeguards: Under heavy load, Wilma can disable message decoding and then disk logging, and restore those operations when load returns to normal. · epam.github.io, 30 Sept 2026
Logging controls: Message logging can be switched on or off from the Wilma UI, and the UI provides access to message log files. · epam.github.io, 30 Sept 2026
Log retention: Wilma has a scheduled process that deletes old message logs according to configurable settings. · epam.github.io, 30 Sept 2026
Message modification: Message interceptors can alter or analyze requests and responses in real time, and users can add their own interceptor classes. · epam.github.io, 30 Sept 2026
Message search: An optional companion application searches request-response pairs logged by Wilma. · github.com, 30 Sept 2026
Operating modes: Wilma can run as a proxy, a service stub, or in a mixed mode. · epam.github.io, 30 Sept 2026
Purpose: Wilma combines a service stub with an HTTP/HTTPS transparent proxy for developing and testing applications that depend on other services. · epam.github.io, 30 Sept 2026
Runtime configuration: Wilma's stub behavior is configured using JSON files, which can be uploaded or changed through its UI or service while it is running. · epam.github.io, 30 Sept 2026
Runtime requirement: The Wilma application requires JRE 11, and Wilma Message Search requires JDK 11. · epam.github.io, 30 Sept 2026
Security and protocols: The introduction says Wilma supports HTTP/HTTPS transparent proxying, including two-way SSL; the repository notes TLS 1.1, 1.2, and 1.3 support for version 2.0, with possible extra configuration. · epam.github.io, 30 Sept 2026
Stub configuration: Stub behavior is configured with JSON files, and multiple stub configurations can be used. · epam.github.io, 30 Sept 2026
Support: The project invites users to submit issues, patches, suggestions, and feedback, and says enterprise support requests can be sent to its contact email. · epam.github.io, 30 Sept 2026
Test scenarios: The maker describes use in unit, integration, functional, end-to-end, and performance testing, as well as manual tests. · github.com, 30 Sept 2026
Traffic handling: It can capture, decode, save, and forward HTTP/HTTPS traffic, including two-way SSL, or generate stub responses for requests. · epam.github.io, 30 Sept 2026
Use cases: The site describes use in development and test environments, including unit, integration, functional, and end-to-end testing, as well as manual testing. · epam.github.io, 30 Sept 2026

Where Wilma stands on Freedom251

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