Functional testing services can increase test coverage and reduce the burden of test creation and maintenance on developers, allowing them to focus on coding new features and updates.
However, during calls with prospects, we often hear about challenges with previous service providers. Namely, testing services that blocked releases, overlooked clear user interface (UI) bugs, and introduced new issues, such as poor communication due to language barriers and time zone differences.
To mitigate these issues, we recommend evaluating testing services based on the following factors:
Do they test the application’s code or visual layer? Most testing services focus only on an application’s code, which can cause them to miss UI bugs. We recommend choosing a service that prioritizes UI testing to ensure a seamless end-user experience.
Do outsourced testers speak fluent English and work in your time zone? Many functional testing services employ testers outside U.S. time zones who may not speak fluent English, leading to communication breakdowns and delays. Opt for a provider with testers fluent in English and aligned with U.S. time zones.
Are outsourced testers dedicated to your account? Many testing services swap out testers regularly, requiring engineering leaders to constantly get new testers up to speed. Partner with a service that assigns dedicated testers so you don’t have to re-explain things.
Can non-technical individuals create and review tests? Code-based testing limits visibility for non-technical product managers, founders, or stakeholders. Choose a service that provides codeless tests so anyone in the company can understand them.
Do they offer both manual and automated functional testing? Some instances require manual testing, while others benefit from automated testing. A reliable testing provider should offer both options.
In this guide, we cover the five best functional testing service providers. We begin with Rainforest QA, detailing our functional testing processes, methodologies, and approach to the factors above.
Schedule a quick demo to see how Rainforest can help you scale testing and ship high-quality code.
1. Rainforest QA
Fast & accurate functional testing services
Rainforest QA offers software testing services that help teams scale functional testing quickly, at a fraction of the cost of full-time QA engineers. We provide regression testing, integration testing, smoke testing, end-to-end testing, exploratory testing, and various other types of testing services.
Here’s how Rainforest tackles the five factors mentioned above:
We use no-code software and entire virtual machines (VMs) to test your application’s visual layer, simulating a real user experience instead of just focusing on the underlying code.
Rainforest’s testing team speaks fluent English and operates in U.S. time zones, minimizing miscommunication and ensuring quick responses.
Test managers integrate into your team’s processes (e.g., Slack, Jira, Trello), which helps them develop an in-depth understanding of your application, much like an in-house QA engineer.
Test managers write tests using natural language scripts, so non-technical founders and product managers can easily see what’s being tested — and even write their own tests.
Rainforest offers a community of manual testers for tests that require human judgment.
Let’s dive deeper into each of these factors.
Factor #1: Rainforest uses proprietary, no-code software to write tests
As mentioned, most testing services focus on evaluating an application’s code, leading to various issues.
Rainforest test managers write tests using our proprietary, no-code software that tests the visual layer, solving these problems.
Below, we’ll highlight four key areas where Rainforest offers a better alternative to code-based testing:
Our proprietary software tests what the end user will see, not the underlying code.
We don’t need to update tests whenever there’s a code change.
We can test everything on screen, including elements outside the browser.
We can create tests 3x faster than testing services that write code-based tests.
Our software tests what the end user will see, not the underlying code
Most functional testing services don’t test user-facing elements directly. Instead, they focus on the application’s code (the DOM), using locators to represent visual elements like buttons, form fields, and images. These locators are then used to verify if the elements function correctly.
However, we’ve found that testing the underlying code isn’t the most reliable way to assess an application’s visual appearance. Locators might be present with all the correct visual settings, but the element can still fail to render properly in the UI. For example:
Tests may verify that text is in the DOM but won’t detect if it’s the same color as the background, making it unreadable.
Tests might confirm a button’s presence in the DOM but won’t catch if it’s hidden behind another element in the visual layer, like an ad or pop-up window.
The best way to test an application is to evaluate the visual layer, just like a human would.
With Rainforest, we evaluate your application’s visual layer using pixel-matching to locate elements. Our tests can uncover bugs that a code-based test might miss.
When test managers create tests inside our no-code functional testing solution, they take a screenshot of the element that needs to be tested and specify the required action (e.g., click, double-click, scroll, type). Rainforest then looks for this screenshot when running tests, rather than relying on element locators in the code.
Here’s a two-minute walkthrough of how tests are created in Rainforest:
We don’t need to update tests whenever there’s a code change
Tests that rely on element locators in the application’s code often break due to code changes, even if those changes have little to no impact on the user experience.
For example, if a developer changes a field ID from “user_email” to “email_input,” the old test script will still search for the “user_email” locator. Since it can’t find it, the test fails and notifies the software development team of a bug, even though the field functions properly. As a result, outsourced services that assess an application’s code need to update their tests after every code change.
This creates three problems:
Outsourced services may delay new releases until all tests are updated and passed, slowing down the launch of new features.
Outsourced services may ignore broken tests to ship new features faster, potentially introducing bugs into production.
Outsourced services may report test failures due to outdated tests instead of actual bugs, leading developers to search for non-existent issues.
To solve this, Rainforest uses pixel-matching to find the visual element that needs testing. Our tests won’t break due to small code changes that don’t impact the visual layer.
That said, intentional changes to the visual layer can break our tests, which is why we can also match against the application’s code and our AI technology:
Rainforest can match against the application’s code: If you know the application’s UI will change in the coming months, but element locators will stay the same, you can match against the code.
Rainforest uses AI trained on human judgment: If the application’s UI and element locator change, Rainforest relies on its patent-pending AI to determine if that change is significant enough for a user to notice. If the change is noticeable, the test fails. However, if the change is inconsequential, say “Next” changed to “Continue,” Rainforest passes the test and alerts developers of the change.
Here’s an example of Rainforest’s patent-pending AI in action:
We can test everything on screen, including elements outside the browser
Most functional testing services use open-source frameworks like Selenium, Playwright, and Cypress to write tests.
The problem with these frameworks is that they can only test actions within the browser tab. You cannot, for example, download a web application or browser extension and see whether it renders correctly on the desktop, nor can you go into the Microsoft Word mobile app to confirm the contents of a document.
Rainforest isn’t limited to just the browser tab. We generate VMs that allow us to test any element on the screen. This enables us to test more complex scenarios, such as opening multiple windows or logging in as different users to test a chat feature.
We can create tests 3 times faster than testing services that write code-based tests
Coding entire test suites for new features can take multiple days. That’s because coding is time intensive — outsourced testers have to write lines of code indicating every element to engage with, its appearance and location, and the action to take.
Rainforest helps teams ship new features faster by creating tests without code. Our testing team writes scripts in plain English, which is three times faster than coding.
Here’s a comparison between coding in open-source testing tools and writing test instructions in Rainforest:
Factor #2: Rainforest test managers speak fluent English and work in your time zone
All Rainforest test managers are fluent in English, minimizing misunderstandings due to language barriers.
Additionally, Rainforest test managers work within U.S. time zones, reducing delays in feedback loops and ensuring fast responses to test instructions, feedback, and updates.
Factor #3: Rainforest test managers are dedicated to your account
A common complaint from prospects who’ve outsourced functional testing is that testers lack a deep understanding of the software application and its functional requirements, leading to ongoing oversight and corrections from engineering leaders.
The issue often arises from system testing companies rotating outsourced testers, which results in a loss of knowledge. Each new tester must learn the application, increasing the risk of missing critical test cases or misunderstanding features.
Rainforest solves this by dedicating two test managers to each client. We don’t rotate test managers like many functional testing services do. Our test managers integrate into your workflows using tools like Slack, Jira, GitHub, Microsoft Teams, Trello, and so on.
As they spend more time creating tests and learning your team’s priorities, they require less oversight. After a few months, engineering leaders can be confident that test managers understand the product as well as an internal hire.
Factor #4: Non-technical individuals can see and create tests in plain English
Outsourced services that write code-based tests operate in black boxes, where only technical employees can understand the tests being run. In some cases, clients don’t even have access to the test scripts, meaning they lack visibility into the actual tests being run.
These services typically focus on meeting a specific coverage percentage without involving the client, which can lead to critical workflows being under-tested and less important areas over-tested.
Rainforest’s no-code tests are easy to create and understand — anyone, even non-technical individuals, can see what’s being tested and immediately assess the application functionality.
We usually accept test instructions through messaging platforms like Slack, so engineering leaders can message their test manager if they want to shift focus to different workflows.
If there’s a break, Rainforest sends video replays (alongside repro steps, screenshots of failed test data, and HTTP logs) to developers through Jira or your preferred project management tool. This makes it easy for them to pinpoint where and why the bug occurred, reducing the time spent diagnosing failures.
Factor #5: Rainforest offers both automated and manual testing services
Newly developed features and applications tend to change frequently, which can make it difficult to create an automated test that won’t break after every run. For these scenarios, manual testing is often more effective than automated tests. Automated testing typically works well for more stable applications.
Considering this, we have a community of crowd testers that you can access (alongside our test managers who run automated tests). These testers will conduct manual tests and return results (in the form of video recordings of the test) in just 17 minutes — the fastest of any manual testing service.
Creating manual tests inside Rainforest is easy. Just write test instructions in plain English, submit them to our community of manual QA testers, and receive a video recording of the test execution. If Rainforest testers find a bug, our platform creates a Jira ticket with the video recording and sends it to the relevant developer.
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2. MuukTest
MuukTest offers agile functional testing services that help development teams ensure their applications function as intended.
By combining automation with manual testing solutions, MuukTest improves software quality while reducing the time developers spend creating and maintaining tests. Their platform is designed to integrate seamlessly with existing workflows, making it easier for teams to detect and resolve issues before they impact users.
Key features
AI-powered automation – Intelligent test automation accelerates bug detection and minimizes human effort.
Seamless integration – Works with popular CI/CD tools, allowing for continuous testing without disrupting development.
Customizable test strategies – Tailored test cases align with business needs and application requirements.
Scalability – Clients can effortlessly scale testing up or down, supporting both small and large teams.
Detailed reporting – Provides detailed insights to help teams quickly diagnose and fix issues.
This guide covers how MuukTest compares to Rainforest QA and other testing services.
3. Test IO
Test IO is an enterprise crowdtesting company that delivers on-demand functional testing services.
Their quality engineering and testing service allows companies to identify issues with their application across different devices, operating systems, and environments. By leveraging human testers instead of relying solely on automation, Test IO can also provide test coverage to newer applications still being developed.
Key features
Manual testing – Applications are tested by real users on real devices, ensuring accurate feedback.
Broad device and OS coverage – Testers use various configurations, uncovering issues across different environments.
Fast results – Although they don’t give a specific number, Test IO promises quick feedback from their team of crowd testers.
Flexible testing options – Supports exploratory, module, usability, and regression testing based on project needs.
Seamless integration – Works alongside existing testing processes, streamlining development workflows.
Read more: Applause vs Rainforest vs Testlio vs Test IO: Crowdtesting Guide
4. Testlio
Testlio offers remote functional testing services that combine expert freelance testers and proprietary technology to help businesses deliver bug-free software.
Testlio’s on-demand testing network allows teams to validate applications across diverse devices, locations, and real-world conditions, ensuring that software functions as expected before release. With a focus on collaborative quality assurance, Testlio integrates directly into development pipelines, enabling faster, more reliable product launches.
Key features
Expert tester network – A vetted, global community of QA professionals conducts thorough functional testing.
Manual testing – Applications are tested across multiple devices, operating systems, and environments.
Flexible testing models – Supports exploratory testing, unit testing, user acceptance testing, and non-functional testing.
Seamless integrations – Works with DevOps pipelines and tools like Jira, Slack, and TestRail.
Scalable and on-demand – Testing adapts to development cycles, from rapid sprints to long-term projects.
5. A1QA
A1QA is a pure-play software testing company that offers functional testing services (regression testing, integration testing, smoke testing, and API testing), helping companies verify that software meets business and user requirements.
Their functional testing services focus on verifying that applications operate correctly across conditions. A1QA’s testing approach includes test plan design, manual and automated testing, and regression analysis to detect issues early in the development lifecycle.
A1QA also integrates functional testing into CI/CD pipelines so companies can receive fast feedback and reduce time to market. Their services also extend across mobile applications, web apps, and enterprise software.
Key features
Fast setup – Automated tests are set up and running within days, minimizing onboarding time.
Parallel test execution – Tests run on a cloud-based infrastructure, delivering quick feedback for CI/CD workflows.
Zero maintenance – A1QA manages test updates, so teams don’t have to maintain scripts.
In-the-loop testing – Expert testers review test results to minimize false positives and flaky tests.
Comprehensive coverage – Functional tests are designed to detect critical bugs across web applications.
Scale functional testing with Rainforest
Book a demo with our team to see how Rainforest can support your workflow.
