Startup Due Diligence Checklist for Investors in 2026

Due diligence on early-stage startups is different from evaluating mature companies. You can't rely on years of financials or proven business models. Instead, you're betting on people, potential, and a product that's barely out of beta.

But that doesn't mean you skip due diligence. You just focus on different things. After investing in dozens of startups at the seed and Series A stage, here's the complete checklist I use to evaluate deals.

Quick Recap: Startup Due Diligence Steps

Here's the startup due diligence process in numbered steps:

1. Initial screening - review pitch deck and ask for data room access
2. Team assessment - evaluate founders and key employees
3. Product review - test the product and talk to users
4. Market validation - research market size and competition
5. Financial analysis - review burn rate, runway, and unit economics
6. Customer diligence - talk to current customers and pipeline
7. Legal review - cap table, IP, and corporate structure
8. Technical assessment - code quality and tech architecture
9. Reference checks - talk to former colleagues and advisors
10. Terms negotiation - finalize valuation and investment terms

Team Evaluation

For early-stage startups, the team is more important than the product. Products pivot, but founders don't.

Founder Assessment

Domain expertise - Do they deeply understand the problem they're solving? The best founders have lived the problem for years. Airbnb founders ran design conferences and needed a way to handle overflow bookings. Stripe founders built payment systems for startups.

Technical capability - If it's a technical product, at least one founder should be able to build it. Non-technical founders building SaaS usually struggle unless they have a strong technical co-founder.

Complementary skills - The best founding teams have:

• Product/technical leader who builds
• Business/sales leader who sells and recruits
• Operator who executes and scales

Three technical co-founders with no business skills or three MBA co-founders with no technical skills both struggle.

Founder commitment - Are they full-time? Do they have enough equity to stay motivated through hard times? Founders with under 10% each post-seed are dilution risks. They'll lose motivation as their ownership shrinks.

Previous exits - Second-time founders with previous exits have:

• Network to hire and fundraise
• Pattern recognition from past mistakes
• Credibility with customers and candidates

But first-time founders can be amazing too - they're often more hungry and creative.

Red Flags in Founders

Frequent pivots - Changing direction every 6 months signals they don't understand their market.

Blame external factors - "We would've hit our numbers but COVID/the economy/competitors..." Great founders adapt.

Can't articulate the vision - If the founder rambles when you ask "what are you building?" they're not clear on their own strategy.

Ego over substance - More focused on press coverage than customer metrics.

Reluctance to share data - Hiding metrics or refusing to open up financials is a huge red flag.

Key Employee Assessment

First 10 hires matter - At seed stage, review each hire. Are they A-players?

Retention - If they've churned through 5 engineers in 12 months, that's a problem.

Leadership bench - Who's the #2 in each function? Strong teams have depth below the founders.

Product and Technology Review

You need to understand what they built, how well it works, and whether it can scale.

Product Testing

Use the product yourself - Don't just watch a demo. Create an account and use it like a customer would.

Core workflow - Can you complete the main use case without hitting bugs or confusing UX?

Performance - Is it fast? Does it handle edge cases?

Mobile experience - If it has a mobile app, test it. Most founders optimize for desktop and neglect mobile.

What's impressive vs. what's janky - Every early product has rough edges. The question is: does the core value proposition work despite the jank?

Talk to Users

Find 5-10 users to interview:

• Why did they start using the product?
• What problem does it solve for them?
• How often do they use it?
• What would they use if this product disappeared?
• What features are missing?

Look for strong engagement signals:

• Daily or weekly active usage
• Users paying (not just free users)
• Users recommending it to colleagues
• Users willing to participate in beta testing or feedback calls

Red flags:

• Users trying it once and never coming back
• "It's nice to have" not "I need this"
• Lots of signups but low activation
• Free users not converting to paid

Technical Architecture

For technical investors or with technical advisors, review:

Code quality - Have a senior engineer review a few pull requests and key modules. Are there tests? Is it documented? Is the architecture sound?

Tech stack - Modern, scalable stack (e.g., React, Node, Python, AWS/GCP) or outdated legacy tech?

Technical debt - Every startup has some. The question is: how much and can they pay it down?

Security - Basic security practices in place? Encrypted data, secure auth, vulnerability scanning?

Scalability - Can the current architecture handle 10x growth without a complete rewrite?

Third-party dependencies - What APIs or services do they rely on? Single points of failure?

Market and Competition

You're betting the market is big enough and growing fast enough to support a valuable company.

Market Size Validation

Don't trust the founder's TAM - Every founder claims a "$100B market." Do your own research.

Bottom-up calculation:

• How many potential customers exist?
• What would they pay per year?
• What % can you realistically capture?

Example: If you're selling €10K/year software to e-commerce companies with 50-500 employees:

• ~30K companies in that segment globally
• If you capture 5% = 1,500 customers
• 1,500 × €10K = €15M potential revenue

That's your realistic addressable market, not the entire global e-commerce software market.

Competitive Analysis

Who are the real competitors?

• Direct competitors (same product, same customer)
• Indirect competitors (different product, same outcome)
• Workarounds (spreadsheets, manual processes)

Competitive advantages:

• What makes this startup win against competitors?
• How defensible is that advantage?
• Can competitors copy it in 6-12 months?

Market positioning:

• Are they cheapest (race to bottom, low margins)
• Best quality (requires ongoing R&D investment)
• Best for a specific niche (defensible but limited upside)

Competitive response:

• What happens when [big incumbent] notices this startup?
• Can they be easily acquired or copied?

Growth Drivers

What will drive growth from here?

• Word of mouth (requires exceptional product)
• Sales team (requires repeatable process and capital)
• Marketing (requires strong conversion and LTV>CAC)
• Partnerships (requires business development skills)

Can they grow faster than the market? If the market grows 10% annually and they're growing 200%, how are they taking share?

Financial Due Diligence

Early-stage financials are simple but still important. You need to understand burn rate, runway, and unit economics.

Revenue Analysis

For pre-revenue startups:

• When will first revenue happen?
• What's the pricing model?
• What assumptions drive the revenue plan?

For startups with revenue:

• Monthly recurring revenue (MRR) or annual run rate (ARR)
• Month-over-month growth rate
• Revenue by customer segment or product line

Revenue quality:

• How much is contracted vs. month-to-month?
• What's the churn rate?
• Are customers paying or using free plans?

Forecasting:

• Do projections match reality?
• If they projected €50K MRR and hit €20K, why the gap?
• Do new projections adjust assumptions or just push dates out?

Burn Rate and Runway

Monthly burn rate - How much cash they spend per month net of revenue.

Runway - How many months until they run out of money.

If they have €800K in the bank and burn €100K/month, they have 8 months of runway.

Red flags:

• Under 6 months of runway (they're fundraising out of desperation)
• Burn increasing faster than revenue (getting less efficient)
• No plan to reach profitability or next funding milestone

Green flags:

• 12+ months of runway (they can focus on building, not fundraising)
• Burn stable or decreasing as % of revenue
• Clear milestones that'll unlock next round

Unit Economics

Even early-stage companies should understand their unit economics:

Customer Acquisition Cost (CAC) - Total sales and marketing spend ÷ new customers acquired.

Lifetime Value (LTV) - Average revenue per customer × gross margin % ÷ monthly churn rate.

LTV:CAC ratio - Should be >3:1 for a healthy business. If you spend €1,000 to acquire a customer, they should generate €3,000+ in gross profit over their lifetime.

Payback period - How many months to recover CAC? Less than 12 months is good, 6 months is great.

For early-stage, these are directional - You don't have enough data for statistical significance. But you should see a path to healthy unit economics.

Customer and Pipeline Review

Talk to customers directly. This is the most valuable part of startup due diligence.

Current Customer Interviews

Ask 5-10 paying customers:

• How did you find this product?
• What problem does it solve?
• What were you using before?
• How much value does it create? (€ saved or revenue generated)
• How likely are you to renew? What would cause you to cancel?
• What features are you waiting for?

Look for patterns:

• Do customers all describe the same core value?
• Are they all in the same industry or use case?
• Do they mention competitors or alternatives?
• Are they evangelists or just satisfied?

Red flags:

• Customers don't seem to get much value
• Using it because it's free, wouldn't pay
• Lots of complaints about missing features
• Considering switching to alternatives

Sales Pipeline Validation

For B2B startups with a sales process:

• How many qualified leads in the pipeline?
• What stage are they in?
• Average deal size and sales cycle length
• Close rate (won deals ÷ opportunities)

Talk to 2-3 prospects in late-stage deals:

• Why are they considering this product?
• What's the buying process and timeline?
• Who else are they evaluating?
• What would it take to close the deal?

If the startup says they have "€2M in pipeline" but prospects say "we're just evaluating, not ready to buy yet," there's a mismatch.

Legal Due Diligence

Even seed-stage companies need clean legal foundations. You're checking for deal-breakers and risks.

Corporate Structure

Incorporation - Incorporated in the right jurisdiction? (For US investors, usually Delaware C-corp. For European investors, often UK Ltd or local equivalent.)

Authorized shares - Enough authorized shares to cover option pool and future funding?

Board composition - Who's on the board? Founder control or investor control?

Corporate records - Clean minutes from board meetings? Proper documentation for past fundraising?

Cap Table Review

Who owns what?

• Founder ownership (should be 60-80% post-seed)
• Employee option pool (typically 10-15%)
• Previous investors (angels, accelerators)

Red flags:

• Founders with under 50% combined (they've given away too much)
• Messy cap table with dozens of small investors
• Unclear or disputed ownership
• SAFEs or convertible notes with terrible terms

Future dilution - After this round, will founders still have enough equity to stay motivated?

IP Ownership

Who owns the technology?

• Did founders assign IP to the company?
• Did contractors and consultants sign IP assignment agreements?
• Any co-founders or early employees who left who might claim IP ownership?

Third-party IP:

• What software or technology is licensed from others?
• Any open source usage with restrictive licenses (GPL)?

Material Contracts

Key agreements to review:

• Customer contracts (terms, pricing, cancellation clauses)
• Vendor agreements (critical suppliers or SaaS tools)
• Office leases (especially if it's a long-term commitment)
• Partnership or reseller agreements

Change of control clauses - Do customers or partners have the right to cancel if the company is acquired? This can kill M&A exits.

Employment Agreements

Founder agreements:

• Vesting schedule (4 years with 1-year cliff is standard)
• IP assignment clauses
• Non-compete and non-solicit (where enforceable)

Key employee contracts:

• Employment vs. contractor status
• Option grants and vesting
• Any unusual compensation arrangements

Compliance and Litigation

Regulatory compliance:

• GDPR for companies handling EU user data
• SOC 2 for B2B SaaS (not always required at seed but good to have)
• Industry-specific regulations (health, finance, etc.)

Litigation:

• Any active lawsuits or disputes?
• Threatened legal action?
• Past settlements or judgments?

Clean legal structure is table stakes. Major legal issues at seed stage = walk away.

Reference Checks

Talk to people who've worked with the founders before. You'll learn things you won't get from the pitch.

Who to Call

Former bosses - How did the founder perform? Strengths and weaknesses?

Former colleagues - What's it like to work with them?

Previous investors or advisors - Why did they invest or advise? Would they do it again?

Customers from previous companies - If the founder has sold to customers before, what was that experience like?

Questions to Ask

Professional competence:

• What are their core strengths?
• Where do they need help or development?
• How do they handle setbacks or bad news?
• How effective are they at recruiting and managing people?

Character and integrity:

• Can you trust them?
• Do they follow through on commitments?
• How do they treat people?
• Would you work with them again?

Founder dynamics (if co-founders):

• How well do they work together?
• How do they handle disagreements?
• Is there a clear leader or equal partnership?

Red flags from references:

• Hesitation when asked "would you work with them again?"
• Mentions of integrity issues or dishonesty
• Pattern of burning bridges
• Excessive ego or difficulty taking feedback

Most investors skip reference checks. Don't. You'll learn critical information.

Setting Up the Data Room

Organized founders create data rooms that make due diligence easy. Disorganized founders make you chase documents.

What Should Be in the Data Room

Company information:

• Pitch deck
• Executive summary
• Company formation documents
• Shareholder agreements

Financial documents:

• Historical financials (last 12-24 months)
• Current cash balance and burn rate
• Budget and forecast
• Cap table

Product and technology:

• Product roadmap
• User metrics and analytics
• Technical architecture overview
• Security and compliance documentation

Customers and sales:

• Customer list (can be anonymized)
• Case studies or testimonials
• Sales pipeline
• Pricing and contracts

Legal documents:

• Previous financing documents (SAFEs, convertible notes, equity rounds)
• Material contracts
• IP assignments
• Employment agreements

Team:

• Org chart
• Bios of key team members
• Option plan

How Papermark Helps Founders

Founders use Papermark to create professional data rooms that make investors happy.

Why it works:

• Easy organization - drag-and-drop folders, clear structure
• Access control - give each investor access to exactly what they need
• Track engagement - see which investors are actually doing diligence
• Answer questions - investors can ask questions on specific documents
• Professional impression - shows you're organized and thoughtful

A well-organized data room signals professionalism. A messy Google Drive folder signals chaos.

Valuation and Terms

Once you've completed diligence and want to invest, you need to agree on valuation and terms.

Typical Seed Valuations

Pre-seed: €2-5M post-money valuation
Seed: €5-10M post-money valuation
Series A: €15-30M post-money valuation

Valuations depend heavily on:

• Traction (revenue, users, growth rate)
• Market size and competitiveness
• Team strength
• How much you're raising

Don't over-optimize valuation. Founders often focus on maximizing valuation at the expense of getting the right investors and terms.

Key Terms to Negotiate

Liquidation preference - 1x non-participating is standard. Avoid participating preferred or multiple liquidation preferences.

Pro rata rights - Investors get the right to invest in future rounds to maintain ownership.

Board seats - At seed, investors typically get 1 board seat or board observer rights.

Protective provisions - Investors can block major decisions (selling the company, raising down rounds, etc.).

Information rights - Investors receive regular financial updates and can inspect company records.

Vesting - Founder shares should vest over 4 years with a 1-year cliff.

Common Startup Due Diligence Mistakes

After reviewing hundreds of early-stage deals, here are the mistakes I see investors make:

Over-relying on the pitch deck - The deck is marketing. Do actual diligence.

Not talking to customers - This is the #1 most valuable diligence step for early-stage companies.

Focusing only on the product - At this stage, team and market matter more than the current product.

Skipping reference checks - You'll learn things that won't come up in pitches.

Overweighting demo day metrics - 6 months of hockey stick growth doesn't mean it's sustainable.

Analysis paralysis - Seed investing requires conviction with incomplete information. Don't over-analyze.

Ignoring red flags - If something feels off, it probably is. Don't talk yourself into a bad deal.

Key Takeaways

Startup due diligence is about evaluating potential, not past performance. Here's what matters most:

• Team first - bet on founders who understand the problem and can execute
• Product validation - use the product yourself and talk to real users
• Market size matters - calculate realistic TAM, not imaginary numbers
• Unit economics - even early-stage companies should show a path to profitability
• Clean legal structure - cap table, IP, and corporate docs should be in order
• Customer diligence - talk to 5-10 customers directly
• Reference checks - validate founder quality through people who've worked with them
• Organized data room - signals professionalism and makes diligence faster
• Trust your instincts - if something feels off, dig deeper

The best early-stage investments combine strong conviction with thorough diligence.

See Papermark data rooms for due diligence

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