What to Design First When Building a SaaS Startup (Priority Order)

One of the most consistent mistakes early-stage SaaS founders make with design is starting in the wrong place. They spend weeks designing a comprehensive product UI before validating that anyone wants the product. Or they launch a well-designed landing page without designing the onboarding experience, then discover that the signups they're generating aren't activating. Or they build a full product before realizing the core workflow is wrong.

Design sequencing matters as much as design quality. Doing excellent design work in the wrong order is expensive and often demoralizing — you've built something polished that turns out to need rethinking. The right order is determined by the decisions you need to make at each stage of building your company.

This guide lays out the priority order that works for most B2B SaaS startups — not as a rigid rule, but as a framework built from watching what succeeds and what gets thrown away.

Priority 1: The Landing Page (Before You Build the Product)

The counterintuitive starting point for SaaS design is the landing page — before you've built meaningful product. Not a placeholder page with an email capture. A page that explains what you're building clearly enough that the right target customer understands it and takes action.

The reason this comes first is that the landing page is the most efficient validation mechanism available. It forces you to answer the most important design questions before committing engineering resources to a product:

Who is this for? A landing page that tries to speak to everyone speaks to no one. Designing the page forces you to pick a primary audience and write copy that resonates with them specifically. If you can't make a clear landing page for your target customer, you don't have a clear enough picture of who that customer is.

What problem does it solve? A landing page that leads with feature lists instead of a clear problem-and-solution statement fails at the most basic communication task. Designing the page forces you to distill your product's value to its most essential form.

Does anyone want this? A landing page with a "Join the waitlist" or "Request early access" CTA generates real signal. The conversion rate — how many relevant visitors request access — tells you whether the positioning is working before you've built anything. According to Y Combinator, the most important early validation metric for consumer and SaaS startups is the number of people who spontaneously try to use what you're building (Y Combinator Startup School, 2023). A converting landing page is evidence of that.

The landing page you build at this stage won't be your final landing page. It will be wrong in specific ways that become clear once you have real users. Design it to be good enough to attract and convert your target customer, not to be a permanent artifact.

Priority 2: The Onboarding Flow (Before You Drive Traffic)

Once you have a landing page that's converting, the instinct is to drive traffic to it — ads, content, cold outreach. Resist that instinct until you've designed a functional onboarding flow.

Here's why: a landing page without onboarding is a leaky bucket. You convert visitors into signups, those signups hit your product and don't know what to do, and they leave — often without ever experiencing the value that caused them to sign up. Worse, you have no data to tell you why they left.

Activation rate — the percentage of new signups who experience meaningful product value — is the single most important metric for early-stage SaaS products. Research from Lenny Rachitsky's survey of B2B SaaS growth benchmarks shows median activation rates between 25–40%, with top-quartile products reaching 60%+ (Lenny's Newsletter, Product Benchmarks, 2024). Most early-stage products have activation rates well below 25% because the onboarding design hasn't been given proper attention.

What to design in the onboarding flow:

The first-run experience. The screen a new user sees when they log in for the first time is the most important screen in your product. It needs to do one thing: show the user the clearest possible path to experiencing your product's core value. Not a feature tour. Not a configuration wizard. One step toward the aha moment.

The setup flow. Every SaaS product has a setup step — connecting an integration, importing data, inviting a team member, configuring a workspace. Design this to require as few steps as possible and to reach value before asking for optional configuration. Set defaults aggressively. Let users reconfigure later.

Empty states. Every section of the product that starts empty needs to explain what goes there and how to add it. Design these before launch. They're the silent activation killer on most early-stage products.

Success moments. Design what happens immediately after a user completes a key action. The first time a user creates a report, runs an analysis, or sends something — what do they see? The success moment reinforces that the action was right and motivates the next one.

Priority 3: Core Product Screens (The Actual Product)

This is where most founders start. It's third on this list for a reason — not because core product design is unimportant, but because designing it before you've validated the market and designed the path into it is the most common form of design waste in early-stage startups.

When you do reach this priority, the key constraint is: design the narrowest possible set of screens that delivers your core value. Your MVP does not need to be comprehensive. It needs to be excellent at one specific thing.

What to design first within the core product:

The primary workflow. If your product is a reporting tool, design the report creation and viewing experience first — not the settings page, not the team management flow, not the integration library. The primary workflow is what your users came for; everything else is supporting infrastructure.

The data displays. B2B SaaS products are predominantly information-dense — tables, charts, timelines, lists. These are the hardest screens to design well and the ones with the most direct impact on user perception of quality. A well-designed data table with appropriate density, sorting, filtering, and inline actions is often more impressive to a B2B buyer than a polished marketing landing page.

Error and edge case states. Design what happens when the API returns an error, when the data set is empty, and when the content is much longer than the designed length. These states are what distinguish a product that feels reliable from one that feels fragile.

Secondary workflows. After the primary workflow is solid: settings, team management, notifications, billing. These matter for retention and growth, but they're not what drives the initial "aha moment."

Priority 4: The Design System (After You Know What You're Building)

Design systems are the highest-leverage design investment for a product that will continue growing. A consistent component library, defined design tokens, and documented patterns accelerate future design and engineering work significantly. They're also the most common premature investment in early-stage SaaS.

Building a design system before you know what you're building is building infrastructure for a building whose floor plan hasn't been decided. The components you create will be wrong in specific ways that only become apparent once users interact with the product. You'll refactor them, and the refactoring is faster and cheaper if you haven't invested heavily in the system documentation.

The right time to invest in a design system is when you have enough designed product to extract real patterns — typically after your core product screens are designed and you've done at least one round of iteration based on user feedback.

At that point, the design system investment does several things:

Accelerates iteration. Changes to a design token propagate everywhere automatically. Updating the button style in the system updates every button in every screen without touching individual frames.

Reduces engineering rework. A component library that engineers can trust reduces the amount of ad-hoc CSS created for each new feature. Consistent components implemented once are maintained more easily than bespoke implementations scattered across the codebase.

Enables faster onboarding. When new designers join (whether in-house or through a subscription), a documented design system dramatically reduces the time before they can produce work that matches your product's patterns.

The practical rule: start creating your design system as you build your core product screens, extracting components as patterns emerge. Don't start with a blank design system and then build screens to fill it.

The Summary Order

1. Landing page — validate the market and force clarity on who you're for
2. Onboarding flow — design the path to first value before driving traffic
3. Core product screens — the primary workflow, then supporting screens
4. Design system — after patterns emerge from the core product

This order is determined by the decisions you need to make at each stage. The landing page validates the idea. The onboarding validates the activation path. The core product validates the value. The design system scales what's working.

For founders at the earliest stage who need to move through priorities 1–3 quickly, Designpixil's MVP design service is structured around exactly this sequencing — landing page through core product screens, in the order that creates the most learning with the least waste.

Frequently Asked Questions