Every European A/B testing tool reviewed
Paris, France
PBX Starter from $495 per month (up to 10 experiments, 50,000 tested visitors per month); Enterprise with unlimited experiments and traffic on request
30-day free trial of PBX Starter, up to 3 experiments, no card required
Best for: Teams that need web testing, server-side testing and feature flags from one European vendor
Kameleoon is the only tool in this category that does not make you choose between the marketing half and the engineering half of experimentation. Web experiments with a visual editor, server-side experiments and feature management are sold as one platform, which is the shape Optimizely has and almost nothing European does. For an organisation that would otherwise buy a testing tool and a flag tool and reconcile two sets of numbers, that is the whole argument.
The company is Kameleoon SAS, registered at 12 rue de la Chaussée d'Antin in the 9th arrondissement of Paris under RCS Aix-en-Provence 507 754 570, with offices in Offenburg, London, New York and Ontario. The privacy policy states that personal data is stored on servers located within the European Union, and the platform runs on dedicated servers rather than public cloud. Kameleoon states ISO 27001 and SOC 2 certification, which no other client-side tool here matches.
Pricing is the honest weak point alongside the detail. PBX Starter is $495 a month for up to ten experiments and 50,000 tested visitors, with a 30-day trial capped at three experiments; everything above that is Enterprise and quoted. And while EU storage is stated, the data centre operator is not named anywhere public, so a procurement team that needs the specific sub-processor will have to ask for it under NDA.
What Kameleoon does well
- Web, server-side and feature experiments in one platform, which nothing else European offers
- ISO 27001 and SOC 2, the strongest stated audit position among the client-side tools here
- French company under EU jurisdiction, with personal data stored on EU servers
- A published entry price of $495 a month rather than a sales call
- 30-day free trial with no card required
Where Kameleoon falls short
- The data centre operator behind "servers within the EU" is not named publicly
- $495 a month is the highest published starting price in this category
- Everything past 50,000 tested visitors a month is a quote
- Not open source, and there is no self-hosted edition
Standout feature. It is the only European vendor here that replaces both halves of Optimizely — Web Experimentation and Feature Experimentation — under one contract and one set of numbers.
Paris, France
Custom quote based on average traffic over the past twelve months or on monthly active users; no public price list
No free trial; a free one-to-two-week proof of concept in a real setup instead
Best for: Large sites that want experimentation and personalisation from an established European vendor
AB Tasty is the biggest European name in this category and sells the widest surface: A/B/n and multivariate testing, a visual editor, goal tracking and real-time reporting as standard, with personalisation and recommendation modules on top.
Roughly 300 staff and more than 1,000 customers as of 2023, with offices in France, the UK, Germany, Spain, the US, Singapore and Sydney. For a large retailer this is a vendor that will still be here in five years and has seen your problem before.
The legal entity is AB Tasty SAS at 17-19 rue Michel Le Comte, 75003 Paris, registered 518 685 540 RCS Paris.
The privacy policy is unusually direct about residency: processed personal data is hosted in the European Union and personal data of visitors to clients' websites is not transferred outside it. AWS in Dublin is named, but only for the email addresses of platform users who sign in with Google — a narrow enough use that it does not undercut the EU claim, though it does mean a US-parented provider sits in the chain.
What AB Tasty will not do is give you a price or a trial.
There is no public price list; quotes are built on average traffic over the past twelve months or on monthly active users depending on the product, and on the modules and implementation scope. There is no free trial either — instead a free one-to-two-week proof of concept in a real setup, which is more useful than a trial but requires a sales relationship to start. Nothing here is self-service.
What AB Tasty does well
- The broadest feature surface of any European tool in this category
- The privacy policy states plainly that visitor personal data stays inside the EU
- French company at a named Paris address under EU jurisdiction
- A free one-to-two-week proof of concept on your real site
- Roughly 300 staff and 1,000+ customers, so vendor continuity is not a question
Where AB Tasty falls short
- No public pricing at all, and quoting is based on last year's traffic
- No free trial and no self-service sign-up
- AWS in Dublin sits in the chain for account email addresses
- No security certification is stated on the public pages checked
- Not open source, with no self-hosted option
Standout feature. Its privacy policy makes the one commitment buyers in this category actually need in writing: visitor personal data is hosted in the EU and is not transferred outside it.
Grünwald, near Munich, Germany
Founded 2019
Growth €199 and Pro €249 per month billed annually (€249 and €349 billed monthly); Enterprise from €499 per month. Unlimited traffic and unlimited team members on every plan
30 days free, no card required
Best for: Teams that want a German-hosted testing tool with a price on the website and unlimited traffic
Varify.io is the clearest answer in this category to the question this site exists to ask.
Varify Software GmbH is registered in Grünwald near Munich under HRB 289569, the product is hosted in Frankfurt, and the site says "Made & Hosted in Germany" rather than the vaguer "EU hosting" everyone else offers. The company was founded in 2019 by three people who had run an A/B testing consultancy for a decade before building the platform, which shows in what they chose to leave out.
The pricing model is genuinely unusual: Growth at €199 and Pro at €249 per month billed annually (€249 and €349 monthly), Enterprise from €499, with unlimited traffic and unlimited team members on every tier. Nobody else here prices on features rather than volume, and for a high-traffic site it changes the arithmetic entirely — a million sessions costs the same as ten thousand. The 30-day free trial needs no card.
The deliberate omissions matter more than the features. Varify has no analytics engine of its own; results are read in GA4, Matomo, Piwik PRO, Snowplow, BigQuery or Clarity, which removes arguments about whose numbers are right and makes the tool useless if you run none of those. It does no server-side testing and has no feature flags, so it replaces Optimizely Web and nothing else. Bayesian statistics, outlier smoothing, API access and role-based access are Pro-tier only.
What Varify.io does well
- Hosted in Frankfurt, stated outright rather than implied — the most specific claim here
- Published prices from €199 a month with no sales call
- Unlimited traffic and unlimited team members on every plan
- Results read in GA4, Matomo, Piwik PRO or BigQuery rather than a proprietary dashboard
- 30-day free trial, no card required
Where Varify.io falls short
- Client-side only: no server-side testing and no feature flags at all
- No analytics of its own, so it is useless without GA4, Matomo or similar already in place
- Bayesian statistics, API access and role-based access need the €249 Pro tier
- The Frankfurt hosting provider is not named
- No security certification is stated, and no free tier below the trial
Standout feature. It charges by capability rather than by traffic, so a site with a million monthly sessions pays the same €199 as a site with ten thousand.
Egham, Surrey, United Kingdom
Founded 2000
Free for sites under 10,000 sessions a month with no feature limits; The Works (managed), DIY (self-service licence) and Hybrid plans all priced on request, scaled on annual sessions
30-day free trial, plus a permanent free tier under 10,000 sessions a month
Best for: Small and mid-sized sites that want a full CRO platform without a contract
Webtrends Optimize has the most useful free tier in this category by a distance: free with no feature limits for any site under 10,000 sessions a month. Not a trial, not a cut-down edition — the full platform, which includes A/B and multivariate testing, server-side testing, personalisation, product recommendations, social proof messaging and surveys. For a site below that threshold, where a test would take months to reach significance anyway, that is exactly the right offer.
The vendor is Accelerate Group Limited, trading as Webtrends Optimize, at Lawrence House, 45 High Street, Egham, Surrey. The testing technology dates back to 2000 and Accelerate Group acquired it in August 2018, so the product is older than the company that runs it. The privacy policy states that all data is stored in Amsterdam, with data collection centres also in Dublin and Australia, and the company is a certified B Corp.
Two things to weigh. The UK sits outside the EEA under an adequacy decision rather than inside the single market, which for some European buyers is a material difference and for others is not; the data itself is in the Netherlands regardless.
And above the free threshold there are no published prices at all — The Works, DIY and Hybrid all read "pricing on request", scaled on annual sessions, so the moment you outgrow the free tier you are in a sales process.
What Webtrends Optimize does well
- Free below 10,000 sessions a month with no feature restrictions
- Full-stack: client-side, server-side, personalisation, recommendations and surveys
- All data stored in Amsterdam, stated in the privacy policy
- Certified B Corp, with a named UK registered address
- 30-day free trial above the free tier
Where Webtrends Optimize falls short
- UK jurisdiction: outside the EEA, under an adequacy decision
- No published prices on any paid tier — all three read "pricing on request"
- Data collection centres in Australia sit outside the EEA
- No security certification stated; B Corp is a governance certification
- Not open source, with no self-hosted option
Standout feature. Below 10,000 sessions a month you get the entire platform for nothing, in a category where the US incumbents start in the tens of thousands per year.
Bucharest, Romania
Founded 2013
Explore free for up to 50,000 tested users a month with the full platform and unlimited tests; paid tiers by traffic band from 50,000 to over 2 million tested users a month, prices shown only after contact, 30% off on annual billing
Free plan, no card required
Best for: Ecommerce teams that want testing, surveys and overlays under one login
Omniconvert was built in 2013 by four people in the corner of a Bucharest advertising agency, on the premise that A/B testing, on-site surveys and overlays belong in one product rather than three. That is still the shape of Omniconvert Explore, and it is the reason to choose it: the survey that tells you why visitors abandon and the test that fixes it live in the same tool, with the same segments applied to both.
The entity is Omniconvert SRL at Str. Vasile Stroescu 14, District 2, Bucharest, registered J40/3841/2013 with VAT ID RO 31411197.
The free plan is unusually serious — the full platform, unlimited tests, for up to 50,000 tested users a month with no card required — and paid tiers step up by traffic band from 50,000 to over two million tested users, with 30% off on annual billing. Explore also covers server-side experiments and native iOS and Android app testing, and offers more than 40 segmentation options.
The gap is transparency about infrastructure. The terms say only that customer data is "stored within the secured Omniconvert infrastructure" — no country, no region, no cloud provider, no sub-processor list on the pages checked. The company is unambiguously Romanian and therefore under EU jurisdiction, but where the data physically sits is a question you will have to ask in writing. Paid prices are likewise not printed; only the free tier carries a number.
What Omniconvert does well
- Free for up to 50,000 tested users a month with the full platform and unlimited tests
- A/B testing, on-site surveys and overlays in one product with shared segments
- Romanian company with a named Bucharest address and registration number, inside the EU
- Server-side experiments and native mobile app testing included
- More than 40 segmentation options, including geo, device and behavioural triggers
Where Omniconvert falls short
- No hosting location published at all — no country, region or cloud provider named
- Paid prices are not printed; only the free tier carries a figure
- No security certification stated on the pages checked
- Built around ecommerce, so content and SaaS teams use less of it
- Not open source, with no self-hosted option
Standout feature. The free plan covers 50,000 tested users a month with no feature gate, which is the point at which most small ecommerce sites can run a real test rather than a trial.
Oslo, Norway
Open Source free and self-hosted with no seat limit (1 project, 2 environments, 5,000 flags per instance); Pay-as-you-go $75 per seat per month with a five-seat minimum; Enterprise on request
14-day free trial, no card required
Best for: Engineering teams that want experimentation they can run on their own infrastructure
Unleash is what you buy when the answer to "where is our data" has to be "on our servers". Bricks Software AS in Oslo publishes an open-source edition that is free, self-hosted and has no limit on seats, so a hundred engineers cost the same as one. Gradual rollouts, variants, environments and a documented API come with it, and the experiment is a consequence of the rollout rather than a separate product.
The hosted product is Pay-as-you-go at $75 per seat per month with a five-seat minimum, or a quoted Enterprise contract, both with a 14-day trial and no card required. Both paid tiers include a choice of EU or US data residency, which is a rarer commitment than it sounds in a category where most vendors say "EU" and stop. Enterprise adds a hosted private instance and multi-region edge.
The limits are real and worth reading before committing. The open-source edition is capped at one project, two environments and 5,000 flags per instance, and leaves out single sign-on, SCIM provisioning, granular access control, change approvals and support SLAs — the exact list a large organisation needs, which is how the licence makes its money.
Norway is in the EEA but not the EU, and there is a US subsidiary, Bricks Software Inc., in the corporate structure. And this is not a marketing tool: there is no visual editor, so changing a headline still takes a deploy.
What Unleash does well
- Open source and free to self-host with no seat limit
- EU or US data residency as a choice on both paid tiers
- Norwegian parent company, with the source available so the deployment can be entirely yours
- Gradual rollouts, variants and environments built for safe releases, not just tests
- 14-day free trial on the hosted product, no card required
Where Unleash falls short
- No visual editor, so a marketer cannot run a test without engineering
- The open-source edition caps at one project, two environments and 5,000 flags
- SSO, SCIM, granular access control and change approvals are paid-only
- $75 per seat is the only per-person price in this category
- Norway is in the EEA but outside the EU, and there is a US subsidiary in the group
Standout feature. It is one of two tools here you can run with no vendor in the chain at all, at any team size, which removes the processor question rather than moving it to a friendlier country.
Helsinki, Finland
Founded 2008
On request; no public price list and no pricing page on the site
Best for: Finnish and Nordic sites that want personalisation with optimisation built in
Frosmo has been doing this longer than most of the category: founded in Helsinki in 2008, at Lautatarhankatu 6, as Frosmo Technologies Oy. The product is a personalisation platform first and a testing tool second — it captures visitor data, acts on it automatically, and runs A/B testing as part of the optimisation loop rather than as a separate workflow you open on Tuesdays.
The residency picture is more specific than most here because the data processing annex names its sub-processors outright: Hetzner Online AG, Hetzner Finland Oy and Amazon Web Services, Inc.
The privacy policy states that personal data of EU/EEA users is not transferred outside the EU/EEA, though it also notes that third-party analytics used on Frosmo's own website may process data on US servers. Naming Hetzner Finland alongside Hetzner Germany is the kind of detail that makes a Nordic procurement conversation short.
What Frosmo does not have is a price. There is no pricing page on the site and no published figure anywhere, which in practice means an enterprise sales cycle and an annual contract.
There is no free tier and no self-service trial either. The automated, AI-driven approach also suits a merchandising team more than an experimentation team: if you want to run a carefully designed hypothesis test with a pre-registered primary metric, this is not the tool built for that ritual.
What Frosmo does well
- Finnish company, founded 2008, with a named Helsinki address
- Sub-processors named outright: Hetzner Online, Hetzner Finland and AWS
- Privacy policy states EU/EEA personal data is not transferred outside the EU/EEA
- Automated, AI-driven optimisation rather than manual test management
- Personalisation and testing in one platform, so segments are shared
Where Frosmo falls short
- Amazon Web Services is a named sub-processor, so a US provider sits in the chain
- No published pricing, no pricing page, and no free tier or self-service trial
- Personalisation-first, so disciplined hypothesis testing is not the primary workflow
- No security certification stated on the pages checked
- Not open source, with no self-hosted option
Standout feature. It is the only vendor here that names its infrastructure sub-processors in its data processing annex, which is the document a Nordic procurement team will ask for first.
London, United Kingdom
Free (50,000 requests a month, one team member, unlimited flags, environments, identities and segments); Start-Up $40 per month billed annually or $45 monthly, which is where A/B testing begins; Scale-Up $250 annually or $300 monthly; Enterprise on request. Overage from $50 per extra million API calls
Free tier rather than a trial
Best for: Developers who want open-source feature flags with A/B testing attached
Flagsmith is the cheapest realistic entry point into experimentation in this category. Bullet Train Limited, company number 12353266, at 66 Paul Street in London, publishes the platform under BSD-3-Clause — a permissive licence rather than a copyleft one, so you can run it, modify it and keep the changes. The free tier covers 50,000 requests a month with one team member and unlimited flags, environments, identities and segments; A/B testing arrives on the $40 Start-Up plan.
The pricing ladder is legible in a way most of this category is not: $40 a month annually or $45 monthly for a million requests and three team members, $250 or $300 for five million and up to twenty, then Enterprise. Overage runs from $50 per additional million API calls and falls with volume. Self-hosting is documented for Docker, Kubernetes with Helm, OpenShift, AWS and Google Cloud, and private cloud can be deployed in a region you pick.
Two caveats. The SaaS hosting story is the vaguest in this category: the pricing page says the cloud is "optimised over eight regions across the world" and does not name any of them, which for a European buyer is not an answer — the practical response is private cloud or self-hosting, both supported.
And the UK sits outside the EEA under an adequacy decision, so a buyer who has made intra-EEA processing a hard requirement will land on Unleash or ConfigCat instead.
What Flagsmith does well
- Open source under BSD-3-Clause, a permissive licence with no copyleft obligation
- Free tier with 50,000 requests, unlimited flags, environments, identities and segments
- A/B testing from $40 a month, the lowest published price in this category
- Self-host on Docker, Kubernetes, OpenShift, AWS or Google Cloud, or private cloud in your chosen region
- Published price ladder including overage rates, with no sales call needed
Where Flagsmith falls short
- The SaaS cloud regions are not named anywhere public
- UK jurisdiction: outside the EEA, under an adequacy decision
- No visual editor, so this replaces Optimizely Feature Experimentation and not Optimizely Web
- The free tier allows a single team member
- No security certification stated on the pages checked
Standout feature. A permissive BSD-3 licence means you can fork it and keep your changes private, which no other tool in this category permits.
Budapest, Hungary
Forever Free $0 (10 flags, 2 environments, 2 products, 5 million config downloads a month); Pro $110; Smart $325; Enterprise $900; Dedicated $4,500 per month. Billable in USD, EUR, GBP or AUD, up to 10% off annually
Forever Free plan, no card required
Best for: Teams that want an audited feature flag service with an EU-only serving option
ConfigCat sells a narrow product well. Feature flags with A/B/n testing through percentage rollouts, user targeting and segmentation, delivered from ConfigCat Kft. at Tátra utca 5/A in Budapest under company registry 01-09-352162. It holds ISO/IEC 27001:2022, publishes a Trust Center with a named sub-processor list, runs a bug bounty and commits to SLAs from 99% to 99.99% depending on tier — a level of documentation most vendors this size do not bother with.
The price ladder is published in full and in four currencies: Forever Free with 10 flags and 5 million config downloads a month, Pro at $110, Smart at $325 with unlimited flags and seats, Enterprise at $900 and a Dedicated private-cloud tier at $4,500 a month. Architecturally it is careful about data: flag values and targeting rules are what ConfigCat stores, and evaluation happens client-side, so your users' attributes need never leave your system.
The honest caveat is infrastructure, and it is the reason ConfigCat sits here rather than higher. The published sub-processor list names Akamai Technologies International AG in Switzerland alongside Amazon Web Services, Cloudflare and DigitalOcean, all United States companies.
The company is Hungarian and therefore under EU jurisdiction, and an "EU Only" data governance setting keeps served config JSONs on EU CDN nodes, but the infrastructure underneath is American. ConfigCat is also unambiguously an engineering tool: no visual editor, and the experimentation reporting leans on integrations with analytics products rather than a dashboard of its own.
What ConfigCat does well
- ISO/IEC 27001:2022 certified, with a Trust Center and a published sub-processor list
- Full price ladder published in USD, EUR, GBP and AUD, from a Forever Free plan
- "EU Only" data governance setting keeps served config JSONs on EU CDN nodes
- Client-side evaluation, so end-user attributes need not reach ConfigCat at all
- Hungarian company under EU jurisdiction, with a Dedicated private-cloud tier available
Where ConfigCat falls short
- Sub-processors are AWS, Cloudflare and DigitalOcean — US infrastructure under a European company
- No visual editor, so this replaces Optimizely Feature Experimentation and not Optimizely Web
- The free plan caps at 10 flags, 2 environments and 2 products
- Experiment reporting depends on integrations rather than a built-in analysis view
- The service itself is not open source, only the SDKs
Standout feature. The "EU Only" data governance setting is the rare case of a vendor building the residency question into the product as a switch rather than answering it in a PDF.
Stockholm, Sweden
On request; no public price list and no pricing page on the site
Best for: Nordic marketing teams that want testing inside the same tool as their campaigns
Symplify Technologies AB sits at Drottninggatan 55 in Stockholm, with offices in Canada, Denmark, Hong Kong and Malta, and describes twenty years of web experience behind the platform. The conversion suite is one part of a larger engagement ecosystem: A/B testing, heatmaps, visitor recordings, personalisation, popups, web push and surveys, all delivered through a single script, sitting alongside the CRM and marketing automation half of the product.
That bundling is the argument. If your campaign emails, your on-site popups and your A/B tests all live in the same platform, the segment you built for one is available to the others and there is no integration to maintain between them. For a gaming, fintech or retail marketing team already looking at a Nordic engagement platform, adding conversion testing is a line item rather than a separate procurement.
The documentation is the weak spot. The privacy policy states that Symplify only works with partners that process personal data within the EU/EEA and that its systems are adapted to Swedish and EU privacy law, but names no data centre, no country and no cloud provider.
There is no pricing page and no published figure. No security certification is stated. And a team that wants a dedicated experimentation platform will find the testing half thinner than Kameleoon or AB Tasty, because it is not the centre of the product.
What Symplify does well
- Swedish company at a named Stockholm address, under EU jurisdiction
- A/B testing, heatmaps, session recordings, popups and surveys through one script
- Testing shares segments with the CRM and marketing automation half of the platform
- Privacy policy commits to partners processing personal data inside the EU/EEA
- Twenty years of web experience behind the product, with offices across four countries
Where Symplify falls short
- No data centre, country or cloud provider named anywhere public
- No pricing page and no published prices at all
- Testing is one module of a wider suite, so it is shallower than a dedicated platform
- No security certification stated on the pages checked
- Not open source, with no self-hosted option
Standout feature. The test and the campaign that follows it run on the same segments in the same tool, which removes the integration every other pairing in this category needs.
Barcelona, Spain
Starter free (500 tested page views a month, one site); Basic 5,000 views and one site; Professional 50,000 views and five sites; Enterprise 200,000 views and unlimited sites — the paid prices are not printed on the pricing page and appear only at checkout, monthly or yearly with 20% off annually
Free Starter plan through wordpress.org, plus a 30-day money-back guarantee on paid plans
Best for: WordPress sites that want to test posts, pages and templates from inside the admin
Nelio A/B Testing is the only tool in this category that understands what a WordPress post is. Built by Nelio Software, S.L. at C/ Pomaret 83 in Barcelona, NIF ESB66034794, it runs inside the WordPress admin and tests the objects WordPress actually has — posts, pages, templates, themes, widgets, menus — rather than asking you to point a visual editor at a DOM element and hope the selector survives the next theme update.
The free Starter plan comes through wordpress.org and covers 500 tested page views a month on one site, which is enough to learn the tool rather than to run a business on it.
Paid tiers step up on tested page views: Basic at 5,000 views and one site, Professional at 50,000 views and five sites, Enterprise at 200,000 views and unlimited sites, monthly or yearly with 20% off annually, and a 30-day money-back guarantee. The company also makes Nelio Content, Session Recordings, Popups and Forms, so the plugins share an account.
Two limits define it. The paid prices are not printed on the pricing page and appear only at checkout, which is an odd choice for a self-service plugin and makes comparison harder than it should be.
And the residency question has no published answer: the legal information page identifies the company clearly but no hosting location, cloud provider or sub-processor list was found on the pages checked. It is also, obviously, WordPress-only — the moment part of your funnel lives elsewhere, this tool cannot see it.
What Nelio A/B Testing does well
- Tests WordPress objects natively — posts, pages, templates, themes, widgets and menus
- Runs inside the WordPress admin, so no separate platform to learn
- Free plan through wordpress.org covering 500 tested page views a month
- Spanish company with a named Barcelona address and NIF, inside the EU
- 30-day money-back guarantee on paid plans
Where Nelio A/B Testing falls short
- WordPress only — useless for any part of the funnel that lives elsewhere
- Paid prices are not shown on the pricing page, only at checkout
- No hosting location, cloud provider or sub-processor list published
- The free plan's 500 tested page views a month will not reach significance on anything
- No security certification stated, and no server-side testing or feature flags
Standout feature. It tests WordPress content types directly instead of CSS selectors, so a theme update does not silently break every running experiment.
