Delivery to proof: conversion rate optimization tools compared

What to take away

Conversion rate optimization tools can deliver variants and calculate results. They cannot repair a vague conversion or poor operational follow-through.

This unpaid, non-ranking comparison covers Optimizely, VWO, AB Tasty and Adobe Target, the four platforms buyers shortlist most often, plus SiteSpect as a server-side alternative. Packaging and prices change, so verify each claim against current vendor documentation during procurement.

1. Optimizely Experimentation

Optimizely pairs web experimentation with its feature flag and content products. Its product page lists visual editing, server-side control, multivariate tests and multi-armed bandits. It also lists stats engine reporting and warehouse connections.

The bandit option suits teams that want traffic shifted toward winners without waiting for a fixed sample. Pricing is quote-based. No public list price exists; Optimizely negotiates annual contracts based on traffic, seats and features. Typical enterprise contracts run from low five figures to mid six figures per year.

Unlike VWO and AB Tasty, Optimizely does not publish a self-serve entry price. Ask which statistical methods, roles and exports sit in the proposed tier.

2. VWO Testing

VWO runs client-side, server-side, split URL and multivariate tests, with Bayesian reporting and rollout controls. It publishes entry-level pricing, which makes it the easiest of the four to pilot on a fixed budget. VWO testing tiers typically start near $100 to $200 per month for small traffic, billed annually, with monthly visitor and test limits.

The trade-off appears at scale: confirm event quotas, identity handling, consent behavior and raw data access for the plan you are quoted.

3. AB Tasty

AB Tasty bundles web and feature experimentation with personalization, and publishes tiered pricing. It suits mid-market teams that want testing and personalization in one contract rather than two vendors. Published tiers typically start in the low hundreds of dollars or euros per month, with limits on traffic and features.

Ask how assignment persists across sessions and how personalization rules interact with running tests, because overlap between the two is where results get muddled. AB Tasty's bundle includes personalization, which can reduce vendor count but complicates test isolation.

4. Adobe Target

Adobe Target sits inside Adobe Experience Cloud, so it makes most sense for teams already running Adobe Analytics or Audience Manager. It supports A/B, multivariate and auto-allocate activities, with reporting tied to the Adobe stack.

Pricing is enterprise and negotiated. No public list price exists; typical Adobe Target contracts run from low five figures to mid six figures per year and are folded into Adobe Experience Cloud agreements. Costs are driven by traffic, activities, seats and which Adobe products you already own.

The advantage is shared identity and audience data. The risk is that leaving the stack means rebuilding integrations. That integration advantage is the strongest among the five for Adobe Analytics users. It is also the hardest exit because audiences and reports live in Adobe Experience Cloud.

5. SiteSpect

SiteSpect runs server-side tests through a proxy or SDK, so it can avoid client-side flicker and tag load. It suits teams with engineering capacity and strict performance or privacy requirements. Pricing is quote-based; no public list price exists. Typical enterprise contracts run from low five figures per year.

Unlike the other four, SiteSpect does not lean on a browser tag as its main delivery model. Ask about proxy routing, rollback, assignment persistence and raw export before you treat it as a drop-in replacement.

How the five tools compare on the seven buying questions

Teams working through those questions often start with a conversion rate optimization checklist so nothing gets skipped.

Run one proof of concept

Give every finalist the same bounded experiment brief. Run it with Optimizely, VWO, AB Tasty, Adobe Target and SiteSpect. Test implementation, assignment, event accuracy, and accessible variants. Check page performance, consent, result interpretation, export, and rollback.

Set pass or fail thresholds before the test. For example, require event match rate within 2 percent of your system of record, and rollback in under 10 minutes. Reconcile test events against your own system of record. Score observed evidence separately from demonstrations and contract promises, and note which vendor needed help to pass.

A sophisticated engine run without a measurement contract or independent review can produce confident-looking mistakes faster.

Decision table

Apply GOV.UK selection criteria to the five tools

The GOV.UK technology selection guidance recommends adaptable choices, data control, security review and ownership-cost analysis. Apply those questions to conversion rate optimization tools; they are not product endorsements. Test Optimizely, VWO, AB Tasty, Adobe Target and SiteSpect against those criteria.

For Optimizely and Adobe Target, ask who owns raw event data and how adaptable the contract is. For VWO and AB Tasty, check data control on the published tier. For SiteSpect, include proxy maintenance in ownership-cost analysis.

The GOV.UK open standards guidance ties open standards to interoperability and reduced supplier dependence. Test whether conversion rate data and definitions can move between platforms without a rebuild. For each of the five tools, ask for the export format and data dictionary in writing.

Common questions

Which CRO tool is best?

None wins outright. Adobe Target suits teams already inside Adobe Experience Cloud. Optimizely suits those wanting experimentation and feature flags together. VWO and AB Tasty suit teams that want published pricing and a faster pilot. SiteSpect suits teams with engineering capacity and strict performance or privacy needs.

Should license price decide the shortlist?

No. Implementation, engineering, data work and training often outweigh the license difference. Analysis, support, migration and exit terms also usually outweigh the license difference. Compare total operating cost across the contract term.

Is a free trial enough to select a platform?

Only if it reproduces your implementation under realistic traffic. Check events, consent, assignment, reporting and export. Then check access controls and rollback. A trial on demo data proves nothing about your stack.

Further reading: Track Event for the JavaScript SDK v6+ (docs.optimizely.com).