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VWO Testing - Server Side

Maximize conversions by building better experiences

Experiment, optimize, and improve conversions on any part of your digital presence with server-side experiments and roll them out behind feature flags without breaking user experience.

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Thousands of global brands trust VWO for their A/B tests and feature management

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Built to help you optimize a diverse set of business goals

I am here to:
Optimize search algorithms with VWO

Optimize search infrastructure to improve click-through rates

A/B test different indexing methods or search-as-a-service vendors to optimize your search infrastructure and achieve lower response times, relevant search results, and contextual autocomplete suggestions.

A/b test recommendations with VWO

Recommend content that catches your audience

Experiment to determine the best analysis systems for thumbnails, such as aesthetic visual analysis (AVA), and improve your watch times

A/b test to find the best pricing options

Optimize pricing tier options to increase orders

Analytically determine the best pricing tier options with different features of your business to hit the right spot between the number of subscriptions and the value of subscriptions.

Optimize to find the best delivery rates with VWO

Experiment with different delivery/shipping fees

Assess the right delivery or shipping fee to charge to your customers without impacting the top-line revenue of your business.

A/B test to find the best security policies

Enhance security without impacting user experience

Experiment with different password policies at sign-up to enhance security without increasing user drop-offs during account creation.

Best TFA strategies to increase daily active users

Choose the better two-factor authentication method

Discover which two-factor authentication techniques are most preferred by your users for their logins.

Rollout features safely with VWO

Schedule release of new features

Create release schedules according to your business requirements to ensure new features are open to specific target groups at the right time.

Rollback features when things turn sour with VWO easily

Rollback features immediately on negative impact *coming soon

Automatically roll back features when a release affects your guardrail metrics negatively to keep the user experience intact.

Optimize strategically with the precision of data-backed decisions

Reliably assess whether your test variations are likely to outperform, underperform, or match the baseline with VWO's accurate, real-time Bayesian-stats-based reports that can handle peeking and multiple testing errors.

Real-time Reports on VWO that facilitate reliable decisions
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Collaborate easily

Share experiment reports via email links, export concise summaries or detailed reports as a CSV, and even print reports to facilitate collaboration.

Optimize any metric with server-side A/b testing
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Optimize any metric from your tech stack

Handpick any metric you wish to optimize, whether standard or custom, and even events from CDPs. Define the direction of improvement and the region of practical equivalence to get accurate conversion performance of each variation.

Next
Enable guardrail metrics that ensure business critical KPIs stay intact during tests
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Test with business safety *Coming Soon

Ensure your optimization experiments do not impact critical business KPIs negatively by enabling guardrail metrics. Automatically pause experiments when your guardrail metrics get negatively impacted.

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Deep dive into segment-specific analysis with report filters
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Uncover granular insights with filters

Filter experiment reports by default options, environments, or custom dimensions for actionable insights. Tailor report views and compare metrics for a complete analysis.

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Get the analytically right decisions backed by Bayesian statistics
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Make confident decisions backed by data

Bayesian-powered Sequential SmartStats gives you precise, trustworthy results for each variation by assessing the likeliness of the variation to outperform, underperform, or match the baseline.

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Get reports in real-time and disable non-performing variation to get to your results faster
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Disable non-performing variations

You can choose any variation as the baseline and disable variations in campaigns when necessary to get results faster.

Next

Deliver winning experiences with robust server-side experimentation and phased releases

Optimize every part of your digital presence with data-driven experiment results, refine your offerings, and progressively roll out features.

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Optimize both form and function

Lightweight SDKs in 8+ languages that support both front-end and back-end to enable optimization of key metrics that impact any part of your tech stack.

Scale your experimentation efforts worry-free

Use as many projects, environments, and feature flags as needed to scale your optimization program and confidently ship complex features.

Clean, reliable, real-time reports

Reliable Bayesian-stats-based, environment-specific reports without traffic from bot user agents and malicious IPs that give you clear, unpolluted decisions.

Feature rollout on VWO

Roll out feature enhancements in phases

Release enhancements to targeted groups first, validate functionality, and only then expand to 100% audience.

Our SDKs enable quick, private, and reliable server-side optimization

VWO offers lightweight SDKs that are easy to integrate and enable cross-platform optimization at high speeds.

Get started in minutes

Our range of open-source SDKs supports both front-end and back-end optimization and can be quickly initialized by your dev team.

View SDK Recipes
Exceptional Speed

SDKs execute API decisions without requiring any external calls to ensure minimum latency and maximum speed.

Learn more
Comprehensive developer documentation

Detailed developer documentation for each SDK and specific methods within SDKs that ensure you rarely face roadblocks.

View SDKs
Ensure experience continuity

Our SDKs maintain uniformity for users within campaigns, ensuring they consistently experience the same test variation once they become part of a campaign.

How SDKs work

Get started in minutes

Our range of open-source SDKs supports both front-end and back-end optimization and can be quickly initialized by your dev team.

View SDK Recipes
//Import the VWO Node SDK to use its features for server-side A/B testing and tracking.const vwoSDK = require('vwo-node-sdk'); // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationconst settingsFile = await vwoSDK.getSettingsFile(accountId, sdkKey) // Initialize the VWO SDK instance with the fetched settings file.const vwoClientInstance = vwoSDK.launch({settingsFile // The settings file obtained from VWO servers.}); // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.const variationName = vwoClientInstance.activate(campaignKey, userId); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwoClientInstance.track(campaignKey, userId, goalIdentifier);
//Import the VWO PHP SDK to use its features for server-side A/B testing and tracking.require_once('vendor/autoload.php');use vwo\VWO; // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operation$settingsFile = VWO::getSettingsFile(accountId, sdkKey)$sdkConfig = ['settingsFile' => $settingsFile]; // Initialize the VWO SDK instance with the fetched settings file.$vwoClientInstance = newVWO($sdkConfig) // The settings file obtained from VWO servers. // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.$variationName = $vwoClientInstance->activate($campaignKey, $userId, $options); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.$vwoClientInstance->track($campaignKey, $userId, $goalIdentifier, $options);
//Import the VWO Python SDK to use its features for server-side A/B testing and tracking.import vwo // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationsettings_file = vwo.get_settings_file(account_id, sdk_key) // Initialize the VWO SDK instance with the fetched settings file.vwo_client_instance = vwo.launch(settings_file)// The settings file obtained from VWO servers. // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.variation_name = vwo_client_instance.activate(campaign_key, user_id); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwo_client_instance.track(campaign_key, user_id, goal_identifeir);
//Import the VWO Javascript SDK to use its features for server-side A/B testing and tracking.const vwoSDK = require('vwo-node-sdk'); // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationconst settingsFile = await vwoSDK.getSettingsFile(accountId, sdkKey) // Initialize the VWO SDK instance with the fetched settings file.const vwoClientInstance = vwoSDK.launch({settingsFile // The settings file obtained from VWO servers.}); // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.const variationName = vwoClientInstance.activate(campaignKey, userId); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwoClientInstance.track(campaignKey, userId, goalIdentifier);
//Import the VWO .Net SDK to use its features for server-side A/B testing and tracking.cusing VWOSdk; // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationSettings settingsFile = VWO.GetSettings(accountId, sdkKey) // Initialize the VWO SDK instance with the fetched settings file.IVWOClient vwoClientInstance = VWO.Launch(settingsFile);public static Dictionary options = new Dictionary(){}; // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.string variationName = vwoClientInstance.Activate(campaignKey, userId, options); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwoClientInstance.Track(campaignKey, userId, goalIdentifier, options);
//Import the VWO Java SDK to use its features for server-side A/B testing and tracking.import com.vwo.VWO; // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationString settingsFile = VWO.getSettingsFile(accountId, sdkKey) // Initialize the VWO SDK instance with the fetched settings file.VWO vwoClientInstance = VWO.launch(settingsFile).build();// The settings file obtained from VWO servers. // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.String variationName = vwoClientInstance.activate(campaignKey, userId, options); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwoClientInstance.track(campaignKey, userId, goalIdentifier, options);
//Import the VWO Ruby SDK to use its features for server-side A/B testing and tracking.require 'vwo' // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationvwo_client_instance = VWO.new(config['account_id'], config['sdk_key'], nil, nil, false) // Initialize the VWO SDK instance with the fetched settings file.options = {} // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.variation_name = vwo_client_instance.activate(campaign_key, user_id, options); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwo_client_instance.track(campaign_key, user_id, goal_identifier, options);
//Import the VWO GO SDK to use its features for server-side A/B testing and tracking.import vwo "github.com/wingify/vwo-go-sdk" // Asynchronously fetch the settings file from VWO servers using your account ID and SDK key.// The settings file contains all the campaign configurations and is essential for the SDK's operationsettingsFile := vwo.GetSettingsFile("accountId", "SDKKey") // Initialize the VWO SDK instance with the fetched settings file.vwoClientInstance, err := vwo.Launch(settingsFile) // The settings file obtained from VWO servers. // Activate a specific campaign for a user. This determines which variation of the campaign the user should see. The method returns the name of the variation assigned to the user.variationName = vwoClientInstance.Activate(campaignKey, userId, options); // Track a conversion (or goal achievement) for a user in a campaign. It is used to record when a user performs a significant action, like making a purchase or clicking a button, contributing to the campaign's success metrics.vwoClientInstance.Track(campaignKey, userId, goalIdentifier, options);

Exceptional Speed

SDKs execute API decisions without requiring any external calls to ensure minimum latency and maximum speed.

Learn more
VWO SDKs load server-side campaigns without making any external network calls

Comprehensive developer documentation

Detailed developer documentation for each SDK and specific methods within SDKs that ensure you rarely face roadblocks.

View SDKs

Ensure experience continuity

Our SDKs maintain uniformity for users within campaigns, ensuring they consistently experience the same test variation once they become part of a campaign.

How SDKs work
VWO helps deliver uniform experiences across campaigns

An arsenal of features that help you experiment the way you want

VWO offers you the flexibility and sophistication to run comprehensive server-side campaigns and improve conversions.

Empower your whole organization with the right experimentation application

Comprehensive experimentation that is easy to set up and scale

Initialize SDKs and get started with server-side experiments in minutes. VWO's support for as many projects and environments as you need makes scaling experimentation a breeze.

Configure experiments

Experiment flexibly

Create any server-side optimization campaign in a jiffy with a simple, easy-to-use UI

Configure experiments

Experiment flexibly

Create any server-side optimization campaign in a jiffy with a simple, easy-to-use UI

Features

Create functional capabilities of your product that you wish to optimize and roll out.

Create features in VWO that server your business logic

Feature tests

Test and iterate feature values with ease behind flags for each variable. Discover winning combinations of values and roll them out with ease.

Determine the best feature variable values on VWO

A/B tests

Hard code complex logic and tailor A/B/n test variations to specific requirements with precise control. Analytically determine the better variation with ease.

Run complex A/B tests and analytically determine winning variations
Choose metrics

Choose any metric you wish to optimize

Choose the metrics you want to optimize, and define the direction of improvement and region of practical equivalence to configure minimum conversion uplift. Add the relevant code snippet to your code base to start tracking the metric. You can even create custom metrics or import events from CDPs like Data360 or Segment.

Explore metrics
Optimize conversions of metrics even from CDPs on VWO
Audience selection

Tailor your test audience

Segment your experiment audience with laser precision using any data - custom variables, OS, behavior, and even third-party events. Craft complex segments using logical operators (AND, OR) and parentheses, save them and repeat your targeting magic across campaigns.

Explore audience selection
Run experiments only for specific target groups on VWO
Reporting

Reports that facilitate decision-making

VWO’s Sequential SmartStats, fueled by Bayesian logic, gauges variations against the baseline. Get the likeliness of each variation to outperform or underperform the baseline. Use report filters for segment-specific analysis and easily toggle between environment-specific and overall reporting.

Explore VWO Reports
Make analytical decisions with Bayesian Real-time reports on VWO
Feature Roll Outs

Roll out enhancements with confidence

Roll out feature enhancements in a phased manner to a selected audience. Assess the impact of the release and release the feature to 100% of users after ensuring there are no code breaks or performance issues.

Rollout features safely, without deploying new code

Leverage the benefits of experimentation across the breadth of your tools

VWO offers integration with tools spanning different categories such as analytics, CMS, call tracking, Data Warehousing, Customer Data Platform (CDP), e-commerce, marketing, productivity, and storage services.

  • Import events from external sources, such as customer data platforms, and use them in your optimization campaigns.
  • Run server-side optimization campaigns on headless CMS such as Contenful seamlessly.
  • Send experimentation data seamlessly using our SDK's callback functions (Node.js) and class methods (Python, Ruby, etc) to analytics tools like Google Analytics, Mixpanel, Amplitude, data warehouses like Amazon Redshift, Google BigQuery, Snowflake, and CDP systems like Segment.com, mParticle.
  • API-based integrations for your custom applications.
View all integrations
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“The VWO-Contentful Integration was the biggest feature that appealed to us. We previously used engineering resources to launch every server-side A/B test. Given our team's large ambitions and limited engineering resources, we could only launch ~1 test every 14-20 days. With the VWO-Contentful integration, we removed the engineering dependency for setting up and launching front-end experiments.”
Nijanth
Nijanth Velmanikandan

Growth Product Manager at Human Interest

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75.84%
Conversion

Human Interest used zero-latency server-side testing to improve conversions on lead forms

Customer Story

Drive your entire optimization program with VWO

Pair Testing with our end-to-end experience optimization platform to enable a data-driven experimentation culture in your business.

Collaboratively build your optimization pipeline

Build a pipeline of high-impact experimentation ideas, collaborate efficiently, and see them to completion. Build a Kanban board workflow with observations to feed your testing and personalization campaigns. Add team members without restrictions and run your optimization program like a breeze.

Explore VWO Plan
Use VWO Plan to collaborate and prioritize tests

Get enterprise-grade security and support from day one

Work confidently, knowing that we have always got your back for your security and support. Build and scale your testing programs with ease.

Your data is safe and secure with us

We value our customers' trust in our platform. Hence, we try our best to comply with security and privacy mandates across physical and digital geographies.

Explore Privacy & Security
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International Organization Standardization Certification

Two-factor authentication (2FA)

Enhance VWO account security with two-factor authentication at the user or workspace level using authenticator apps or email passcodes.

Data storage

VWO has data centers in the US, the EU (Belgium), and India. Our CDN uses a load balancer, is hosted on Google Cloud Platform, and spans 10 locations from Japan to Brazil for faster loading.

Dedicated customer success manager

Leverage our training programs and dedicated success manager to optimize your website for better conversions.

Support with a constant CSAT of ~99%

You can count on us all year round for your most minor query while running the most complex experiments. Our technical experts will guide you all year round.

Single sign-on (SSO)

Log into VWO securely and conveniently using SAML 2.0-based single sign-on via identity providers like Google, Azure Cloud, OneLogin, Okta, and others.

Role-based permissions

Get Sub-accounts and varying levels of user permissions to bifurcate testing for client/agency and role division for the enterprise.

Delight your users by giving them a great experience. Start optimizing today!

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Frequently Asked Questions

Server-side testing is a method of A/B testing wherein the variations of a particular test are rendered directly from the server & then deliberately sent to the visitors’ device.

A feature is an addition or modification to the system that adds new functionality. A product’s features define it and set it apart from other similar products. From a business perspective, a feature should have characteristics that make it practical, easy to use, and efficient.

A feature flag is a software development approach that allows for the remote activation or deactivation of functionality without the need for code deployment. With feature flags, it is possible to introduce new features at runtime without additional code.

A feature flag can regulate access, for instance, if new features are made accessible to internal users for testing and feedback. The functionality is only visible to employees connected to the program using a corporate email address. Feature flags enable you to classify risk and manage components. By separating deployment from release, feature flags enable you to control a feature’s entire lifespan and opt for secure testing in production mode.

Feature testing is the procedure that is performed when a new feature is introduced to the application, or an existing feature is modified. It can also be defined as the process used to test several iterations of the feature to find the most successful version that offers the greatest user experience.

VWO SDKs are directly integrated with your servers and make no external calls to return variations to be assigned to users. The entire decision time is less than 50ms and will have no noticeable impact on your page loads.