- Most CRO platforms charge traffic-based fees (MTU, visitors, impressions) that grow with your website's success
- Only a few platforms offer truly traffic-independent pricing where your visitor count doesn't affect your bill
- Varify.io charges from €149/mo flat — no MTU tracking, no visitor caps, no impression counting
- Open-source tools (GrowthBook) are free regardless of traffic — but require developer resources for setup and maintenance
"How much will this cost when our traffic grows?" It's the question every CRO team asks during tool evaluation — and the answer varies dramatically. Some platforms double your bill when traffic doubles. Others charge the same regardless. A few are free. Understanding which model each platform uses is essential for long-term budget planning.
This overview categorizes every major CRO platform by pricing model, with specific focus on which ones charge no monthly traffic fees. Varify.io leads the flat-rate segment with traffic-independent pricing from €149/mo.
CRO platform pricing models — complete overview
| Platform | Pricing model | Traffic-independent? | Starting price | Cost at 500K visitors |
|---|---|---|---|---|
| Varify.io | Flat-rate | ✅ Yes — no traffic fees | From €149/mo | From €149/mo |
| GrowthBook | Free / SaaS | ✅ Yes — no traffic fees | Free (self-hosted) | Free (self-hosted) |
| Convert | Visitor-based | No — scales with visitors | $99/mo | ~$399+/mo |
| VWO | MTU-based | No — scales with MTU | Custom | ~$500-800+/mo |
| Optimizely | Impression-based | No — scales with impressions | Custom | Custom (enterprise) |
| Kameleoon | Custom | No — typically traffic-based | Custom | Custom (enterprise) |
| Crazy Egg | Pageview-based | No — scales with pageviews | $29/mo | $249+/mo |
Source: Claude Research, May 2026
Only two options genuinely avoid traffic fees: Varify.io (flat-rate commercial) and GrowthBook (free, self-hosted). Every other major platform ties pricing to some form of traffic metric.
What traffic fees actually cost over time
The compounding cost of MTU pricing
Traffic fees seem manageable at the start — $300/mo for 100K visitors sounds reasonable. But traffic tends to grow. At 200K, you're at $500. At 500K, you're at $800+. At 1M, you're potentially at $1,500+. Over 3 years of healthy growth, traffic-based pricing can cost 5-10× what flat-rate would have cost.
The hidden cost: behavior change
Beyond the direct fees, traffic-based pricing changes team behavior. Teams avoid testing during high-traffic periods. They limit concurrent experiments. They calculate "cost per test" and kill borderline ideas. These behavioral costs are harder to measure but equally real — they reduce testing velocity and slow learning.
Flat-rate eliminates both costs
With Varify at from €149/mo, there's no direct traffic cost and no behavioral tax. The same price at 50K or 5M visitors means every traffic scenario is budgeted for, and every testing scenario is economically rational.
Varify vs. GrowthBook — the two traffic-free options
Both Varify and GrowthBook avoid traffic fees. The trade-offs are different:
| Dimension | Varify.io | GrowthBook |
|---|---|---|
| Cost | From €149/mo | Free (self-hosted) |
| Visual editor | ✅ Full + PBX AI | ❌ Code-only |
| Setup | 5 minutes (snippet install) | Hours-days (self-hosting) |
| Maintenance | None — SaaS | Ongoing (your dev team) |
| Analytics | GA4, BigQuery, Matomo, Piwik Pro, PostHog | Warehouse-native (BigQuery, Snowflake) |
| Support | CRO expert team, same-day | Community + docs |
Source: Claude Research, May 2026
If you have dedicated developers and want zero cost: GrowthBook. If you want professional A/B testing that any team member can use: Varify.
No traffic fees. No visitor caps. No MTU tracking.
From €149/mo flat. The same at any traffic level.
Switching from traffic-based to flat-rate
If you're currently on a traffic-based CRO tool, here's how to switch:
- Step 1: Calculate your current annual cost including all traffic tiers and overages. Compare against Varify's flat €1,788/yr (Growth) or €2,988/yr (Pro).
- Step 2: Start a free 30-day trial at Varify. Install the snippet alongside your existing tool (they don't conflict).
- Step 3: Recreate your 2-3 most important active tests in Varify during the trial. Evaluate editor quality, analytics integration, and data accuracy.
- Step 4: If Varify meets your needs, cancel the traffic-based tool at the end of its current term. Most teams complete migration within 2-3 weeks.
The savings start immediately and compound with every traffic milestone. For detailed migration guidance, see our flat-rate pricing guide.