# TryFast: A/B testing for teams and AI agents, hosted in Germany

Try ideas fast. Ship the ones that win.

Change a headline, a button or a whole page for some of your visitors and see which version converts better. TryFast tells you in plain words when a result is safe to act on, and your AI agent can set up the test for you.

[Start free, no account](https://tryfast.eu/app/zero-account-setup) (no card, no account needed, live in about 2 minutes) or [connect your AI agent](https://tryfast.eu/ai-agents.md).

## Why teams choose TryFast

- **Hosted in Germany**: servers in Nuremberg, a company in Berlin, EU law.
- **Under 12 KB**: the script your visitors load, compressed. One request.
- **Check results any time**: statistics that stay valid however often you look.
- **Works with your AI agent**: Claude, ChatGPT, Cursor and VS Code, through one URL.

Live numbers: [TryFast in numbers](https://tryfast.eu/stats.md).

## How it works

1. **Paste one line.** Add the snippet to your site, or let your AI agent do it, and connect your cookie banner with one more line. We show you when the snippet loads and when the first visitor is counted.
2. **Make the change.** Click and edit in the visual editor on your own site, write CSS and JavaScript, or describe the change to your agent. Preview every variation before anyone sees it.
3. **Launch and get a verdict.** TryFast splits your visitors, counts conversions and tells you what to do: ship it, keep the original, or keep collecting.

No account needed. Save your workspace to an account whenever you like.

## Built for AI agents: your agent builds the test, you approve the launch

TryFast works with MCP, the open standard AI agents use to work with tools. Connect once and ask in plain language: your agent looks at the page, writes the variation, sends you preview links and asks before anything goes live.

```bash
claude mcp add --transport http tryfast https://tryfast.eu/mcp
```

Works with Claude Code, Claude, ChatGPT, Cursor and VS Code.

- Launches wait for your approval unless you grant full access.
- Every agent action appears in the activity log with the agent's name.
- Results are safe to check in a loop, so agents never call a winner too early.

An example session:

> **You**: Test a free shipping headline on acme-shop.de/pricing against the current one. Goal: more people starting checkout.
>
> **Claude** (`inspect_page`, `create_experiment`, `get_preview_link`): The headline is `#hero h1`, "Simple plans for every shop". I created the draft "Free shipping headline": Variation B reads "Free shipping on every order". Goal: Started checkout. Preview B on your site: acme-shop.de/pricing?tf_preview=... At about 4,500 visitors a day, detecting a 10% lift takes about four weeks; a larger effect shows sooner.
>
> **Claude** (`start_experiment`, awaiting approval): Ready to launch. Approve it here: tryfast.eu/app/approve/apr_8f2kQ7xLm1

More: [How TryFast works with AI agents](https://tryfast.eu/ai-agents.md).

## Everything a testing team needs, nothing it does not

- **Visual editor**: click any element on your own site to change its text or style, hide it, or insert HTML. No browser extension.
- **Code editor**: CSS and JavaScript per variation, checked when you save, with the exact line of any error. On every plan.
- **Split URL tests**: send some visitors to a different page. Query strings stay, both sides are counted the same way.
- **Targeting**: pages, devices, new or returning visitors, UTM parameters, cookies and your own visitor attributes.
- **Goals and revenue**: clicks, page visits, custom events and revenue. Duplicate orders count once.
- **Preview links**: share a link that shows one variation on your live site, on any device, without touching results.
- **Health checks**: traffic split, tracking and mixing checks every hour. A broken split blocks the ship verdict.
- **Single-page apps**: React, Next.js, Vue and others: route changes are picked up without extra code.
- **API and activity log**: every action through a documented REST API, and a log of who changed what, people and agents alike.

## Statistics you can trust: check as often as you like

Most A/B testing statistics are only right if you look once, at the planned end. People look every morning, and AI agents look every hour; each look raises the chance of crowning a winner that is not one. TryFast uses sequential statistics by default: the intervals account for every look, so a result marked safe to act stays right.

- A verdict in words: ship it, keep the original, keep collecting, or check your data.
- Every lift comes with its 95% interval. No interval, no number.
- Traffic split checks every hour. If the split is off, we block the ship verdict and say why.
- More than one variation or goal? We adjust for it and tell you so.
- Prefer Bayesian chance to win or a fixed sample size? Choose per experiment.

Example: on day 3, Variation B looks +15%, but the interval runs from −20% to +66%: too early. On day 10 the whole interval is above 0: safe to act. [How we calculate results](https://tryfast.eu/docs/statistics.md).

## EU and privacy: your visitors' data stays in Germany

- **Hosted in Germany.** Servers in Nuremberg, backups in Germany. Every subprocessor is listed publicly.
- **A company in Berlin.** Operated by subprocess.eu/company, Osloer Str. 83, 13359 Berlin, under German and EU law.
- **Consent first.** By default TryFast waits for your cookie banner and stores nothing before consent. One line connects Cookiebot, Usercentrics, OneTrust and others.
- **No IP addresses stored.** We count visitors with a random id, never with their IP address.
- **One cookie, 390 days at most.** A single first-party cookie, within the 13-month limit EU regulators recommend.
- **A DPA on every plan.** A data processing agreement under Art. 28 GDPR is part of our terms.

[Privacy policy](https://tryfast.eu/legal/privacy-policy.md), [Data processing agreement](https://tryfast.eu/legal/data-processing-agreement.md), [Subprocessors](https://tryfast.eu/legal/subprocessors.md), [Compliance](https://tryfast.eu/legal/compliance.md).

## Fast for your visitors

| Figure | What | Detail |
|---|---|---|
| Under 12 KB | Script | Compressed engine. Your experiments add only their own changes. |
| 1 | Request | Engine and experiments arrive together, no second round trip before your page shows. |
| 2 minutes | To every visitor | Launches, pauses and stops reach everyone within two minutes. |
| No eval | Strict CSP friendly | Variation code is checked and built ahead of time. |

While experiments load, the page is hidden for at most 800 ms by default, and only on pages with an experiment.

## How TryFast compares

We checked public pricing pages, documentation and live scripts in October 2026. Where others do more, we say so.

| | TryFast | Kameleoon | VWO | Optimizely |
|---|---|---|---|---|
| Published prices | Free, €49 and €249 per month | From $495 per month (Starter) | On request | On request, annual contracts |
| Free plan | 25,000 tested users a month | 30-day trial | None listed | None |
| Start without an account | Yes | No | No | No |
| Where data is hosted | Germany | EU or US | US, EU (Belgium) or India | EU hosting available |
| Default statistics | Sequential, valid at any time | Frequentist; sequential and Bayesian available | Bayesian | Sequential |
| Code editor | Every plan | Paid add-on on Starter | Included | Included |
| Visual editor | Text, styles, hide, remove, insert HTML | Full graphic editor | Full visual editor | Full visual editor |
| AI agents (MCP) | Builds, previews and launches web experiments; launches need your approval by default | Remote server for experiments and flags | Local server for feature flags only | Remote server; web variation code is edited in the visual editor only |
| Script your visitors load | Under 12 KB engine, compressed | 49 to 183 KB compressed on five live sites we measured | Not measured by us | Not measured by us |
| Personalization, feature flags, multivariate tests | Not yet | Yes | Yes | Yes |

Checked 24 October 2026 from kameleoon.com, wingify.com/pricing, optimizely.com and each vendor's MCP documentation. Script sizes are brotli-compressed file sizes of the per-site script on five public Kameleoon customer sites. Tell us at support@tryfast.eu if something has changed.

## Pricing: free to start, fair as you grow

- **Free**: €0. 2 projects, 25,000 tested users a month, every feature.
- **Pro**: €49 per month. 10 projects, 250,000 tested users.
- **Business**: €249 per month. Unlimited projects, 2 million tested users, priority support.
- **Enterprise**: custom. A dedicated server and your own limits.

[Compare plans](https://tryfast.eu/pricing.md).

## Questions, answered

### Is TryFast really free?

Yes. The free plan has every feature, 2 projects and 25,000 tested users a month, with no card and no time limit. You pay only when you need more projects or traffic.

### Do I need an account to start?

No. Enter your website and you get a workspace right away. It is kept in your browser; save it to an account any time to keep it for good and invite your team.

### Will TryFast slow down my website?

The script is under 12 KB compressed and arrives in one request with your experiments inside. On pages with an experiment, the page waits at most 800 ms by default so visitors never see the original flash before the variation.

### Does A/B testing need a cookie banner?

In Germany and most EU countries, yes: A/B testing is not covered by the exemptions for strictly necessary cookies. TryFast waits for your banner by default and stores nothing before consent. Our [privacy docs](https://tryfast.eu/docs/privacy-and-consent.md) explain each option.

### How do AI agents use TryFast?

TryFast has an MCP server at https://tryfast.eu/mcp. Add it to Claude, ChatGPT, Cursor or VS Code and your agent can install the snippet, look at your pages, build experiments, share preview links and read results.

### Can my AI agent launch an experiment without asking me?

Not by default. When you connect an agent you choose its permission. With the default, the agent prepares everything and sends you an approval link; nothing goes live until you click it. Pausing is always allowed.

### Why can I check the results whenever I want?

TryFast uses sequential statistics. The intervals are built to stay valid no matter how often you or your agent look, so checking daily does not create false winners.

### Does it work with React, Next.js and other single-page apps?

Yes. Route changes are detected automatically and experiments are applied again on every new page. For custom rendering you can call `tryfast.refresh()`.

### Where is my data stored?

On Hetzner servers in Nuremberg, Germany, with backups in Germany, operated by a company in Berlin. Visitor IP addresses are not stored. The [subprocessors page](https://tryfast.eu/legal/subprocessors.md) lists every provider involved.

### Can I switch from Kameleoon, VWO or Optimizely?

Yes. The concepts carry over one to one: experiments, variations, goals and targeting. There is no automatic import yet; most teams rebuild their running tests in an afternoon, or ask their AI agent to do it from the old code.

### What happens to a workspace I never save to an account?

It keeps working while you use it. After 30 days without use it pauses: running experiments pause and your snippet stops changing your site. Save it to an account and you can resume them where they left off. After 90 days without use it is deleted.

[Read the docs](https://tryfast.eu/docs/index.md). [What TryFast does not do yet](https://tryfast.eu/docs/limitations.md).

## Your first experiment can be live in two minutes

Paste one line, make one change, and let your visitors decide. [Start free, no account](https://tryfast.eu/app/zero-account-setup) or [compare plans](https://tryfast.eu/pricing.md).