SaaS that bills right.
SaaS software development built for customer one thousand, not just the demo.
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Senior engineers
No juniors. No middlemen.
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Fixed price
Overruns are on us.
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Live in weeks
Weekly demos on staging.
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You own the code
100% of the IP, day one.
SaaS software development is building a subscription product many customers share. The hard parts are rarely features: tenant isolation, billing edge cases (trials, proration, failed payments, tax), onboarding and churn analytics. Yarify, a senior team in Prague, builds new SaaS products at a fixed price for agreed scope and runs dedicated teams for SaaS companies already selling. We have shipped multilingual Stripe checkout, country-based pricing and referral attribution in production.
The four places SaaS breaks
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Tenant isolation
Enforced at the data layer
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Billing edge cases
Idempotent, reconciled Stripe webhooks
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Onboarding
Activation measured from week one
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Security questionnaires
SSO, roles, audit logs planned
A demo is easy. Billing is not.
Stalled SaaS products fail the same way: tenant checks scattered across controllers, Stripe webhooks that charge twice, pricing hard-coded in the frontend, no event tracking.
None of it shows up in a demo, so junior-heavy agencies skip it. SaaS software development done right starts there.
SaaS software development we ship
Delivered to a staging URL you click every week.
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Multi-tenant core
Organisations, workspaces, invitations, roles and permissions, with tenant context enforced once per request.
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Subscription billing
Stripe Billing, customer portal, plans, usage metering, country-based pricing, tax handling and webhook reconciliation.
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Onboarding flows
Sign-up, guided setup, sample data and checklists that move a trial to its first real outcome.
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Churn analytics
Activation and retention cohorts, MRR dashboards and health scores that flag at-risk accounts before renewal.
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Admin and back office
Impersonation with audit trail, refunds, plan overrides and feature flags for support and finance.
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AI features
LLM features with per-tenant cost controls and evaluation. See AI development.
SaaS we have shipped
Astrooly: Stripe checkout in three languages, country-based pricing, referral attribution, admin dashboard. A content automation platform running on about an hour of maintenance a month.
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Astrooly: Paid SaaS in Three Languages
Multilingual astrology SaaS: natal chart engine, AI-assisted readings, Stripe checkout in 3 languages with country pricing, server-side referral attribution, admin dashboard, GTM analytics.
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Five Platforms, One Hour a Month
Internal platform for a marketing agency: generates short-form video from three inputs and publishes to YouTube, Instagram, Threads, Reddit and Telegram. Spring Boot, Next.js, MongoDB.
From scope to launch
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Written scope, fixed price · Week 1
Tenant model, billing model, roles and the one workflow your first version must nail.
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Foundations · Weeks 2–3
Auth, organisations, tenant isolation, CI/CD, staging, Stripe in test mode.
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Core workflow · Weeks 3–8
The feature customers pay for. Weekly demos, pull requests in your repo.
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Harden and launch
Activation events, monitoring, backups and a security pass. Then handover, or we continue as your dedicated team.
Agency SaaS build vs ours
What usually happens
- A project manager relays questions to juniors
- Billing bolted on at the end
- Tenant checks scattered everywhere
- No analytics until after launch
- Code in the agency's repo
How we build SaaS
- You talk to the senior engineer writing the code
- Stripe wired in week two, failure cases tested
- Isolation enforced at the data layer
- Activation events defined before the UI
- Your repo, your cloud, your IP
What moves the price
Market data puts most MVPs at $15k–$150k. Full breakdown in our [SaaS development cost guide](/cost/saas-development-cost).
- How strict tenant isolation must be
- Pricing model: flat plans or usage metering across countries
- Number of user roles and integrations
- SSO and audit requirements for enterprise buyers
- AI features with per-tenant cost controls
Fixed price. We eat the overruns.
For fixed-scope SaaS builds, the quoted price for the agreed written scope is what you pay. If our estimate was wrong, the extra hours are our cost. Changes you request are quoted separately first.
How our MVP builds workRelated services and guides
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SaaS development
SaaS products built on solid foundations: multi-tenancy, Stripe subscriptions, auth and roles, admin dashboards and product analytics. Fixed quote for the first version.
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MVP development
Fixed-price MVP development. A senior team scopes it in writing, ships a deployed build early, demos weekly and launches a focused MVP in typically 8–12 weeks.
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SaaS development cost
What it costs to build a SaaS product in 2026: launch ranges, the SaaS-specific features that add hours (billing, multi-tenancy, SSO), region rates and running costs.
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Next.js developers
Senior Next.js engineers for App Router builds, Pages Router migrations, caching and SEO fixes, Stripe and auth. Join your team monthly or own a fixed-price build.
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Software rescue
Stalled at 80%? Vendor vanished? AI-generated code nobody understands? We audit it for free, tell you to salvage, refactor or rebuild, then fix it for a fixed price.
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Fixed price vs T&M
Fixed price or time and materials for your software project? Who carries the risk, what each really costs, a numeric overrun example and when to use each model.
Questions buyers ask us
How long does it take to build a SaaS product?
Most first versions we scope take two to four months, depending on tenant model, billing complexity and integrations. Week one produces a written scope and fixed price, and you click a working staging URL within the first few weeks.
Should a SaaS be multi-tenant from the start?
Almost always. Retrofitting tenant isolation touches every query, background job and file upload, and it is one of the most expensive rewrites in SaaS. Building organisations and roles into version one costs little extra.
Which tech stack do you use for SaaS development?
Usually Next.js and TypeScript, a backend in Node.js, Java/Spring Boot or Python, PostgreSQL or MongoDB, Stripe and Google Cloud or AWS. Boring, well-supported tools your next hire knows. If you have a stack, we work in it.
Can you take over a SaaS another agency built?
Yes. It starts with a free code audit: a senior engineer gives a written verdict on what is healthy, what is risky and whether to keep, refactor or rebuild, with a fixed quote for the fix if you want it.
Do you handle Stripe tax, VAT and international pricing?
Yes. We shipped Stripe checkout in three languages with country-based pricing for Astrooly. We set up Stripe Tax or your provider, handle EU VAT IDs and reconcile invoices with your database. Tax advice comes from your accountant.
Who owns the code and the customer data?
You do. Code lives in your repository from the first commit, infrastructure runs in your cloud account and 100% of the IP is yours. Dedicated teams are billed monthly with two weeks' notice.
Keep reading
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SaaS development
SaaS products built on solid foundations: multi-tenancy, Stripe subscriptions, auth and roles, admin dashboards and product analytics. Fixed quote for the first version.
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SaaS development cost
What it costs to build a SaaS product in 2026: launch ranges, the SaaS-specific features that add hours (billing, multi-tenancy, SSO), region rates and running costs.
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Astrooly: Paid SaaS in Three Languages
Multilingual astrology SaaS: natal chart engine, AI-assisted readings, Stripe checkout in 3 languages with country pricing, server-side referral attribution, admin dashboard, GTM analytics.
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MVP development
Fixed-price MVP development. A senior team scopes it in writing, ships a deployed build early, demos weekly and launches a focused MVP in typically 8–12 weeks.
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Fintech
Payment flows, trading and execution engines, risk controls, reconciliation and audit trails built by senior engineers who treat every cent as a test case.
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Healthcare
Clinical tools, patient portals and medical AI software with audit logs, consent handling and human-in-the-loop review designed in from the first sprint.
Your SaaS, billed correctly from customer one.
Book a free 30-minute scoping call. A written scope and a fixed price, not a 40-page proposal.