Automated Java Unit Testing

Diffblue Cover catches changes to code behavior and regressions earlier in your pipeline using the most advanced reinforcement learning techniques available. Diffblue’s free plugin for IntelliJ will enable you to create 1000s of tests with minimal effort.


public void getCover() {

You’re wasting your time writing unit tests

On average, a single unit test can take 10 minutes for someone to write and execute.

It takes Diffblue Cover 10 seconds.

Run Diffblue Cover after you've written new code and it will create your tests and check coverage while you're grabbing a coffee.


unit tests generated

of developer time saved

Based on a developer working for 6 hours a day, 254 days a year, and a unit test taking on average 10 minutes to write.

Human-readable tests, written by machines

Diffblue tests are written in clear, straightforward language so that you can quickly understand what's changed and fix regressions and other bugs in your code.

Take a look at this test - it was written by Diffblue Cover.

20@ContextConfiguration(classes = {AmazonS3.class, CloudStorageService.class})
public class CloudStorageServiceDiffblueTest {
  private AmazonS3 amazonS3;

  private CloudStorageService cloudStorageService;
  public void testUploadFileToBucket() throws SdkClientException {
    // Arrange
    PutObjectResult putObjectResult = new PutObjectResult();
    when(this.amazonS3.putObject(anyString(), anyString(), (File) any())).thenReturn(putObjectResult);

    // Act and Assert
    assertSame(putObjectResult, this.cloudStorageService.uploadFileToBucket(
        "bucket-name", "object-key", Paths.get(System.getProperty(""), "test.txt").toFile()));
    verify(this.amazonS3).putObject(anyString(), anyString(), (File) any());

Obtain high coverage

Our technology analyzes your entire Java applications to provide more coverage than is practical (or even possible) to write manually, letting you finally hit your code coverage targets.

Tackle that insurmountable legacy code

Working with a heap of legacy code you don’t want to break?

Run Diffblue Cover tests to better understand how this code behaves and interacts with your new code.

Who can use Diffblue Cover?

Our IntelliJ Plugin, Diffblue Cover: Community Edition, can be used to analyze any code, whether it's open source or commercial, for free, for any individual user. 

We offer a pro version for our commercial customers who require premium support and indemnification. We also offer a CLI version of Diffblue Cover, which is perfect for teams to use together. 

Word of Mouth

"Diffblue Cover is enabling us to improve quality and build new software, faster."Read Case Study >

Matt Davey

Managing Director at Goldman Sachs

Goldman Sachs

"[Diffblue] enable[s] optimization of our existing products, services or technologies"Read Blog Post >

Linda Newman

Head of Technology Strategy at S&P Global Ratings

S&P Global Ratings

"We're greatly benefiting from Diffblue to keep our customers secure."

Michael Tautschnig

Research Scientist at AWS



Free IntelliJ Plugin

Diffblue Cover Community Edition for IntelliJ writes Java unit tests for your code.

It’s 100% free to use to generate unit tests for open-source or commercial projects.

Diffblue Cover CLI for Teams

A powerful and customizable tool that unlocks hidden dependencies within your code, to provide a holistic understanding of your environment for everyone on your development team.

  • Premium Support
  • CI Integration
  • Full Idemenification
  • Built for Teams
  • Enhanced Reporting
  • Risk free - 30 day cancellation

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Diffblue is changing the way software
is developed using artificial intelligence

Architectural changes while modernizing your infrastructure result in the isolation of code, which increases risk. Our aim is to enable every developer to create and run thousands of unit tests with minimal effort, optimize code coverage, and decrease the risk associated with deploying new code.

Automating test generation with Diffblue Cover helps your team deliver products faster while avoiding unnecessary costs, gaining a competitive advantage, and having visibility of tangible coverage metrics that track your success.