Three principles before the list
Most tool-stack articles show you what a funded team uses. This one assumes you're solo, have customers paying you, and need to protect your margin. Three rules shape every recommendation here.
First: flat pricing beats usage pricing early. When you have 50 customers, a €49/month flat SaaS is predictable. A tool charging €0.80 per user per month sounds cheap until you're at 300 customers paying €600/month for something that should cost €50. Flat plans give you breathing room to grow.
Second: one integrated tool beats three specialists. You don't have time to maintain Zapier bridges between your CRM, email platform, and support desk. If a single tool does email and basic CRM adequately, use it. Save the specialist tools for when one category becomes your bottleneck.
Third: skip analytics theatre. You don't need heatmaps, session recordings, funnel visualization, and cohort retention dashboards when you have 100 customers. You need to know where signups come from and which features get used. Anything beyond that is procrastination dressed as data-driven decision-making.
Domain and hosting: €120/year total
Register your domain at Namecheap or Porkbun. Budget €12/year. Avoid GoDaddy's upsell maze and the registrars that hold your domain hostage during transfers. You want boring reliability, not a relationship.
For hosting your marketing site, you have two paths. If you're building with Marcus, hosting is included in your €29/month Builder plan, your site deploys to our edge network, and you're done. If you're using a static site generator, Netlify's free tier handles 100GB bandwidth and gives you forms and serverless functions. Vercel's free tier is similar. Both charge when you cross thresholds, but a marketing site for a B2B SaaS won't hit them.
Total here: €12/year for domain, €0-29/month for site hosting depending on your builder. Call it €120/year combined if you're using Marcus for your site and product marketing.
Marketing site: €29-290/month
This is where you explain what you do, publish comparison pages, host your pricing calculator, and convert organic search into signups. You need something you can edit yourself without a deploy cycle.
Marcus Builder at €29/month is built for exactly this. You get the marketing site, landing pages, a blog with proper SEO metadata, and form handling. Edit in plain English, publish in seconds, no Git workflow. If you're running lifecycle emails and need deeper analytics as you scale, Marcus Studio at €290/month adds customer data infrastructure and multivariate testing, but wait until you're past 500 customers.
The alternative is a WordPress install on a €8/month VPS. Maintenance burden is real, updates break things, and you'll spend four hours a month keeping plugins compatible. Only go this route if you already know WordPress deeply and enjoy that specific kind of suffering.
What to skip: website builders with content limits
Many no-code website builders charge per page or cap your blog at 20 posts. You're building a content moat through SEO. You need to publish 60 comparison articles, 40 how-to guides, and 15 case studies over two years without hitting artificial limits. Choose tools that charge for capability, not volume.
Product: €0-500/month depending on architecture
If you're building a web app, this is your biggest variable cost. The smart move: build on a platform that scales pricing with your revenue, not your activity.
For SaaS products with standard CRUD operations, Railway or Render give you a Postgres database, application hosting, and background workers starting at €15-20/month. At 100 customers doing normal database reads, you're around €80/month. This grows gradually. You're not paying for Redis, monitoring, log aggregation, and six other services individually.
For apps that can run serverless, Vercel or Netlify combined with PlanetScale's database starts free and costs roughly €30/month at moderate usage. The trade-off: you architect differently, cold starts matter, and some operations get awkward. But your hosting bill stays low while you prove revenue.
If you're using Marcus to build your product, it's included in the Builder plan. You design your app structure, we handle the infrastructure. No separate hosting bill, no scaling concerns until you're well past 100 customers.
What to skip: Kubernetes, microservices, multiple environments
You don't need a staging environment that mirrors production when you're solo. Test locally, use feature flags, deploy to production during low-traffic hours. You definitely don't need container orchestration. One dyno or one server running your app is enough until you have reliability problems, which won't happen at 100 customers.
Payments: 1.5-2.9% + €0.25 per transaction
Stripe is the answer. Their cut is 1.5% + €0.25 for European cards, 2.9% + €0.25 for international. At 100 customers paying €50/month, that's €5,000 revenue and roughly €100 in fees. Non-negotiable cost of doing business.
You get payment processing, subscription management, invoicing, tax calculation through Stripe Tax (1% of transaction volume where applicable), and a customer portal where users update their cards. All through one integration.
Do not build your own recurring billing logic. Do not use a payment processor that makes you handle subscription state yourself. Stripe Billing manages upgrades, downgrades, prorations, failed payments, and dunning. You call their API and render their components. Worth every basis point.
What to skip: payment orchestration layers
Services that sit between you and Stripe to "optimize" payment routing or retry logic charge €200-500/month minimum. You don't have the volume to benefit. Stripe's built-in Smart Retries handle most failed payments. Add orchestration when you're doing €100k/month and can A/B test routing strategies.
Email and basic CRM: €50-80/month
You need to send transactional emails (password resets, receipts), onboarding sequences, and occasional lifecycle campaigns. You also need to track which customers are engaged and which haven't logged in for 60 days.
Loops at €50/month gives you email sends, basic segmentation, and contact properties. Clean interface, good deliverability, generous send limits. For solo founders, it's enough. Alternatively, Customer.io starts at €80/month but adds better event tracking and SMS, useful if your product has time-sensitive notifications.
These tools combine your email platform and lightweight CRM. You're not managing contacts in one system and emails in another. One source of truth, one bill.
If you're on Marcus Studio, customer messaging and segmentation is built in. You define triggers based on user behavior, write the message, and it sends. No separate integration.
What to skip: full marketing automation suites
HubSpot, Marketo, and ActiveCampaign are built for marketing teams running lead scoring, multi-touch attribution, and complex nurture tracks. At 100 customers, you need three email sequences: onboarding, re-engagement, and feature announcements. Save €300/month and use a focused tool.
Support: €0-50/month
Your customers will email you. You need those emails organized, tagged, and responded to without losing threads.
Start with a shared inbox like Front (€9/month per seat, so €9 for you) or Missive (€14/month). Both turn your support@ email into a proper ticketing system with assignments, snoozing, and canned responses. You can add a second person later without re-architecting.
Plain is another option at €40/month, designed specifically for small B2B SaaS. Threads automatically link to customer records, and you can see product usage alongside the conversation. Useful once you're handling 50+ support requests monthly.
At 100 customers, you're probably answering 80-120 emails a month. You don't need live chat, chatbots, or a knowledge base with search analytics. Write good docs, link to them in your onboarding emails, and answer the rest personally. This is a competitive advantage while you're small.
What to skip: Intercom, Zendesk
These platforms start around €60/month but push you toward €200+/month plans with live chat widgets, help center hosting, and bot automation. You're solo. You don't staff live chat. You write better docs instead. Use the expensive support tools when support itself becomes a hiring bottleneck.
Analytics: €0-30/month
You need to know where your traffic comes from, which pages convert, and how people use your product. You don't need pixel-perfect session replays.
Plausible at €9/month gives you privacy-friendly web analytics with clean UTM tracking and goal funnels. Good enough for your marketing site. For product analytics, PostHog's free tier covers 1 million events monthly. Track feature usage, build basic funnels, and export data when you need it. If you cross their free tier, the paid plan starts at €30/month.
Between these two tools, you answer: What content drives signups? Which features do active customers use? Where do people drop off during onboarding? That's your entire analytics requirement at this stage.
Marcus Builder includes basic analytics. Traffic sources, page views, conversion events. Studio adds cohort analysis and feature usage tracking. If you're already using Marcus for your site and product, you're covered.
What to skip: FullStory, Hotjar, Mixpanel premium tiers
Session recording tools cost €80-200/month and generate hundreds of hours of videos you'll never watch. Heatmaps show you where people click, which matters for e-commerce checkout flows but barely matters for B2B SaaS workflows. Advanced product analytics with unlimited funnels costs €300+/month. Wait until you have a product team to justify this spending.
Accounting and invoicing: €15-40/month
You need to track expenses, reconcile Stripe payouts, and generate reports for your accountant at year-end. If you're VAT-registered, you need compliant invoices.
QuickBooks Self-Employed at €15/month handles expense categorization, mileage tracking, and quarterly tax estimates. It connects to your bank and Stripe, imports transactions, and exports reports. Sufficient for a solo founder doing simple bookkeeping.
If you need proper double-entry accounting, Xero at €30/month is cleaner than QuickBooks' main product and integrates well with European banks. You can invite your accountant as a free user, and they can run reports directly. Worth the extra €15 if you're managing multiple revenue streams or have inventory.
Stripe automatically generates invoices for subscriptions. For any one-off project work, use the invoicing feature in QuickBooks or Xero. Don't pay separately for invoicing software.
What to skip: FreshBooks, enterprise accounting platforms
FreshBooks is invoicing software pretending to be accounting software. It costs the same as Xero but does less. Sage, NetSuite, and other enterprise tools are built for companies with purchase orders, inventory management, and multi-entity consolidation. Your accountant will tell you when you've outgrown Xero.
Total monthly cost: €553 at 100 customers
Here's the realistic breakdown when you're at 100 customers each paying €50/month:
- Domain and DNS: €10/month (amortized)
- Marketing site (Marcus Builder): €29/month
- Product hosting: €80/month (Railway/Render estimate)
- Stripe fees: ~€100/month (2% of €5,000 MRR)
- Email and CRM: €50/month
- Support inbox: €40/month
- Analytics: €9/month (Plausible only, PostHog free tier)
- Accounting: €30/month
Total: €348/month in fixed costs, €100/month in variable payment processing. That's €448/month, or 9% of your MRR. Add another €100/month buffer for miscellaneous services (password manager, file storage, backup tools), and you're at €553/month all-in.
If you use Marcus for both marketing site and product, your hosting and infrastructure consolidates to €29/month, bringing the total to €398/month. The difference compounds: €1,860/year saved is meaningful runway when you're bootstrapped.
When to upgrade each category
This stack gets you to €10k MRR comfortably. Beyond that, specific categories will show strain before others. Here's what breaks first.
Email and CRM breaks at 500 customers. You'll need better segmentation, more sophisticated automation, and the ability to build conditional workflows without code. That's when you evaluate Customer.io's higher tiers or consider tools like Loops' team plan.
Support breaks at 200 tickets/month. When you're spending 30+ hours weekly in your inbox, you need canned responses, assignment rules, and SLA tracking. Plain or Help Scout make sense here. You might also hire your first support contractor, which changes the economics.
Analytics breaks when you have a product team. Solo, you make decisions based on conversations with customers and usage patterns you can see in simple dashboards. Once you have a product manager or designer, they need self-service access to data. That's when PostHog's paid tier or Amplitude's starter plan earn their cost.
Accounting breaks when you raise funding or hire. Payroll, equity management, and investor reporting need different tools. Xero plus a payroll service like Deel handles the first employees. Beyond 10 people, you'll hire an accounting firm that brings their own stack.
The principle: upgrade a category when the current tool stops you from shipping or causes you to lose money through inefficiency. Upgrading because a feature exists is how you end up at €2,000/month in SaaS costs with the same revenue.