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The European comparison: SimplyBoost, Watermelon and Trengo, all from Utrecht, with Sleak and Userlike alongside, on how they charge, what a busy month costs, which channels and languages they cover, where the data lives and how handover works. One winner, and the cases where the others fit.
Three of the AI customer service tools a European business will shortlist in 2027 come from the same Dutch city. SimplyBoost, Watermelon and Trengo were all built in Utrecht, and they have made three different bets: an AI agent priced flat, a chatbot priced per conversation, and a shared inbox priced per user with AI on top. Sleak, from Tilburg, and Userlike, from Cologne, round out the European field. This comparison puts them side by side on the things that decide the purchase, with every figure taken from the vendors' own pricing pages on 27 October 2026.
I work on SimplyBoost, so the verdict is not neutral. The numbers are, and every vendor name links to the page the figure came from.
The short answer
SimplyBoost is the best choice for most European businesses: one AI agent on website chat, WhatsApp and Instagram, 500 to 6,000 AI replies included for a flat €39, €89 or €169 a month, three agents and your team seats included, hosted in Europe with a data processing agreement. Watermelon suits a Dutch team that prefers to pay per conversation and stays under 1,000 conversations a month. Trengo suits a team of ten or more people who answer most conversations themselves and want email, phone and messaging in one inbox. Sleak suits a Dutch-only website chatbot. Userlike suits a German team that wants a multichannel inbox priced per seat.
How each one charges
SimplyBoost charges by AI replies: €39 for 500, €89 for 2,000, €169 for 6,000 a month, €31, €71 and €135 on yearly billing. Seats, channels, calendar booking, lead capture and handover are in the price, and every plan includes three AI agents and the owner plus two teammates.
Watermelon charges by conversations, where every message within 96 hours counts as one conversation. The free plan covers 50 a month, Starter €99 for 250, Advanced €199 for 500, Business €399 for 1,000. Each plan includes one user and one AI agent, and every extra user or agent costs €25 a month. Yearly billing is 15 percent cheaper.
Trengo charges by users and conversations, with the AI on top. Boost costs €349 a month, or €299 billed yearly, for ten users and 500 conversations; Pro costs €599, or €499 yearly, for twenty users and 1,500 conversations. Extra conversations cost €15 to €18 per hundred, and every conversation the HelpMate AI agent handles adds €0.25 on yearly billing or €0.30 on monthly.
Sleak charges €69 a month, or €59 billed yearly, for the Start plan with 300 conversations, then €0.09 per conversation after that; Grow is €119 (€99 yearly) and Scale €229 (€199 yearly), each with the same 300 conversations included. Userlike prices per seat and sells its AI agent as an add-on from the Pro plan; it does not publish the figures, so ask.
What a busy month costs
Take five people and 2,000 conversations in one month, with the AI handling most of them. This is the calculation that separates the brochures.
SimplyBoost: the Growth plan at €89, flat, with 2,000 AI replies. One conversation can hold several replies, so a heavy month may push you to Pro at €169. Either way the bill is a plan price, not a surprise.
Watermelon: 2,000 conversations is above the published plans, which stop at Business with 1,000 for €399. Four extra users add €100. You are at €499 for the first thousand conversations and a custom quote for the second.
Trengo: Boost at €299 yearly covers 500 conversations, so 1,500 extra conversations add €225 to €270, and 2,000 AI conversations at €0.25 add €500. That is roughly €1,025 to €1,070 a month. Pro at €499 lands in the same range once the extras are counted.
Sleak: Start at €59 yearly plus 1,700 extra conversations at €0.09 comes to about €212, with one AI agent and a website-first product. Honest and cheap for website chat, but you are not getting WhatsApp or Instagram yet.
Channels
SimplyBoost includes website chat, WhatsApp and Instagram DMs and comment replies on every plan, with the same agent and knowledge base. Watermelon integrates WhatsApp, Instagram DM, Facebook Messenger and email in its plans. Trengo is the widest inbox: email, WhatsApp, Instagram, Facebook, live chat, voice and SMS. Sleak lists WhatsApp as beta and Instagram DM, email and Messenger for the fourth quarter of 2026. Userlike covers chat, WhatsApp, Instagram, SMS and email.
If your question is "which tool answers my WhatsApp and Instagram customers with AI, today, in the plan price", the answer is SimplyBoost. If your question is "which inbox lets twenty people share email and phone calls", the answer is Trengo.
Languages
SimplyBoost replies in the language the customer writes in, or in a fixed language you choose per agent: Dutch, French, German, Spanish or English, from one knowledge base. That matters for a Dutch webshop with Belgian and German customers, and for a holiday park that hears four languages a day. Sleak presents itself as a Dutch chatbot for Dutch businesses. Watermelon, Trengo and Userlike serve international customers; check how each handles a second language in the trial, with a real German or French question.
Hosting and the data processing agreement
All five are European companies, which already answers the first procurement question. SimplyBoost is hosted in Europe with a data processing agreement you can download, deletes conversations after 360 days and uses Google Gemini as the model. Watermelon states EU hosting on Google Cloud. Trengo, Sleak and Userlike are Dutch and German companies; ask each for the hosting location, the agreement, the retention period and the AI model in writing, the same four questions you would ask an American vendor.
Handover to people
SimplyBoost hands over on a complaint, a refund, a legal question, two unanswered questions, the word "human" or any of twenty keywords you choose, to email, Slack, the shared inbox or a ticket in Zendesk, Freshdesk or Gorgias, with the whole conversation attached. Trengo's handover is its strength, because the inbox is the product: the AI hands to the same inbox your team lives in. Watermelon hands over inside its own inbox, where email sits next to chat. Sleak hands over through integrations with external systems. For a team that already runs a helpdesk, SimplyBoost's ticket handover means you keep it; for a team that wants the inbox to be the tool, Trengo is the natural fit.
Where each one wins
SimplyBoost wins on price predictability, included channels, languages and speed to live: most businesses answer real customers within a day of pasting their website. Watermelon wins for a Dutch team that wants per-conversation pricing and modest volume. Trengo wins for large shared-inbox teams with phone and email. Sleak wins for a Dutch-only website chatbot at a low entry price. Userlike wins for a German team that values a seat-based inbox from a German provider.
The verdict for 2027
For a European business whose customers write on WhatsApp, Instagram and the website, and who wants to know the bill before the month starts, SimplyBoost is the best of the Dutch tools and, we would argue, the best AI customer support choice in Europe. Run the 7-day trial with last month's twenty questions, then price the same month on the Watermelon alternative and Trengo alternative pages, which carry the same figures with sources.
Frequently asked questions
Is SimplyBoost better than Watermelon?
For most teams, yes. €39 a month buys 500 AI replies, three AI agents and three people on SimplyBoost, where Watermelon's Starter costs €99 for 250 conversations with one user and one agent. Both are from Utrecht and both host in Europe; SimplyBoost includes WhatsApp and Instagram on every plan.
Is SimplyBoost better than Trengo?
For businesses that want AI to answer first, yes. Trengo starts at €299 a month on yearly billing for ten users and adds €0.25 to €0.30 for every AI conversation; SimplyBoost includes the AI replies in a flat €39, €89 or €169. Trengo is the better choice for a large team that needs email, phone and messaging in one shared inbox.
What is the difference between Watermelon and Trengo?
Watermelon is an AI chatbot priced per conversation, with one user and one agent per plan. Trengo is a shared omnichannel inbox priced per user bundle, with an AI agent that costs extra per conversation. One is AI-first for small teams, the other inbox-first for larger ones.
Which Dutch AI customer service tool is cheapest?
At the entry level, SimplyBoost at €39 a month, then Sleak at €59 on yearly billing, Watermelon at €99 and Trengo at €299. At 2,000 conversations a month the gap widens: SimplyBoost stays at a plan price while Watermelon needs a custom quote and Trengo passes €1,000.
Which one includes WhatsApp and Instagram?
SimplyBoost includes both on every plan. Watermelon and Trengo integrate both within their plans. Sleak lists WhatsApp as beta and Instagram as planned. Userlike covers both as part of its inbox.
Are these tools GDPR compliant?
All five are European companies. SimplyBoost is hosted in Europe with a data processing agreement, 360-day retention and Google Gemini as the model; Watermelon states EU hosting on Google Cloud. Ask each vendor for the hosting location, the agreement, the retention period and the AI model in writing.
Which is best for a Shopify webshop?
SimplyBoost, because the agent shows order status and tracking after an email code check, starts returns, and on the Growth plan recommends products and builds a cart with a checkout link, on the website, WhatsApp and Instagram. Watermelon integrates with Shopify, WooCommerce, Returnless and Monta; Trengo lists Shopify, WooCommerce, Magento and Lightspeed.
Which is best for Belgium?
SimplyBoost answers in Dutch and French from one knowledge base, which covers both language communities without two setups. Our Belgian customer service page explains the setup.
Can I switch from Watermelon or Trengo without losing anything?
Yes. SimplyBoost learns from your website and documents rather than old chat logs, so you start by adding those. Your WhatsApp Business number moves through Meta's embedded signup; a number is connected to one platform at a time, so plan that moment. Most switches are done in a day.
What does Sleak cost compared with SimplyBoost?
Sleak Start costs €69 a month, or €59 billed yearly, with 300 conversations and €0.09 per extra conversation, with WhatsApp in beta. SimplyBoost starts at €39 with 500 AI replies, three agents, and WhatsApp and Instagram live.