Top 10 Free Startup Due Diligence Tools (2026)
Due diligence doesn't require a Bloomberg terminal or a CB Insights subscription. Some of the best signal-gathering tools are either free or have generous free tiers. Here's what the top solo GPs and angels actually use to verify startup claims without spending anything.
1. Google — The First Research Tool (Free)
Before any other tool, start with Google. The goal isn't to find the company's website — it's to find what the rest of the world says about them.
What to search:
- "[Company name] controversy"
- "[Company name] lawsuit"
- "[Founder name] startup"
- "[Company name] review"
What you're looking for: News coverage, user complaints, industry discussion. Most signal failures show up in the first page of results.
Free tier: Everything. Google is free.
2. LinkedIn — Team Verification (Free Tier)
LinkedIn is the fastest way to verify founder claims about their own backgrounds.
What to check:
- Employment timeline — does it match what the founder claimed?
- Company pages — does the company have a real presence?
- Connections — who else has worked there, and does that validate the story?
- Recommendations — anyone willing to publicly endorse this person?
What to watch for: Timeline gaps, exaggeration of role scope, "advisor" titles that look honorary.
Free tier: Basic search and profile viewing is free. Some advanced features require Sales Navigator (free trial available).
3. Crunchbase — Funding History (Free Tier)
Crunchbase tracks funding rounds, investor names, and company announcements going back years.
What to check:
- Funding history — how much have they raised, from whom?
- Lead investors — top-tier names validate the deal; unknown names are a yellow flag
- Board members — listed board members should match what the company claims
- News — Crunchbase curates funding announcements and can surface previous company outcomes for founders
What to watch for: Discrepancies between deck claims and actual funding history. Some founders claim valuations that don't match public filings.
Free tier: Crunchbase Free gives you basic funding data. Full historical data requires a paid subscription, but the free tier covers most seed and Series A companies.
4. Google News — Recent Coverage (Free)
Search the company's name in Google News to see what journalists and bloggers have written about them in the last year.
What to look for: Press coverage that validates or contradicts their pitch. PR that reads like advertorials vs. genuine third-party coverage.
What to watch for: No coverage at all for a company that claims significant traction. Or coverage that only appears in small, unknown publications.
Free tier: Completely free. Set a Google Alert for the company name so new coverage surfaces automatically.
5. SimilarWeb — Traffic Intelligence (Free Tier)
SimilarWeb gives you estimated website traffic, top traffic sources, and geographic distribution — without asking the company for anything.
What to check:
- Is the traffic real? Sudden spikes followed by drops are a red flag
- Where does traffic come from? Direct vs. organic vs. referral tells you whether users are finding them or they're buying traffic
- Geographic distribution — a B2B SaaS should have different geographic patterns than a consumer app
- Competitor comparison — how does their traffic compare to similar-stage companies?
What to watch for: Traffic claims in the deck that don't match SimilarWeb estimates. A company claiming viral growth with flat traffic is lying.
Free tier: SimilarWeb Free gives you top-level estimates. For full data, paid plans start around $99/month — but the free tier is often enough to catch major discrepancies.
6. Hunter.io — Team Email Verification (Free Tier)
Hunter.io finds email addresses associated with a company domain. This is useful for verifying that the people the company claims to have hired actually exist.
What to check:
- Can you find email addresses for the team members listed in the deck?
- Are they using company email domains or personal Gmail accounts?
- What's the company's email infrastructure — is it Google Workspace, Outlook, or something generic?
What to watch for: No Hunter results for a company that claims 50 employees. Or team members using personal email instead of company domains (less of a red flag for early-stage, more of one for later stage).
Free tier: 25 searches/month free. Enough for checking a handful of key contacts on each deal.
7. OpenCorporates — Legal Entity Verification (Free)
OpenCorporates lets you look up legal entities in most US states and many international jurisdictions.
What to check:
- Is the company legally registered where they say they are?
- Who are the listed officers and directors?
- Have there been any name changes, mergers, or prior entities?
- Any liens or filings that suggest financial stress?
What to watch for: Operating under a different legal name than what the deck says. Officers that don't match the founder claims.
Free tier: Basic search is free. Detailed reports require a subscription, but the free tier covers most initial checks.
8. G2 and Capterra — Product Reviews (Free)
If the company claims customers love their product, look for evidence on G2, Capterra, or Trustpilot.
What to check:
- Are there reviews? For early-stage companies, zero reviews is a yellow flag (they haven't been live long enough to accumulate many)
- What do reviews say? Look for patterns — both positive and negative
- When were the reviews posted? A cluster of new reviews after a funding round is worth noting
What to watch for: Five-star reviews that all use similar language (astroturfing). No reviews for a company claiming enterprise customers.
Free tier: Searching and reading reviews is completely free. Writing reviews requires registration.
9. LinkedIn Jobs — Hiring Verification (Free)
The company's job postings tell you what's actually being built. A company claiming to be "almost launched" with no open engineering roles is a red flag.
What to check:
- What roles are they hiring? Engineering, sales, marketing — the mix tells you what they're optimizing for
- How many open roles? Rapid hiring signals growth; slow hiring signals caution
- Seniority level — hiring mostly juniors suggests early stage; hiring VPs and directors suggests later stage
- Job post dates — how recent are postings?
What to watch for: "AI-powered" companies with no ML or AI-related roles. Enterprise companies with no sales hiring. Hardware companies with no hardware engineers.
Free tier: LinkedIn search is free. Applying to jobs or viewing full job details requires LinkedIn (free accounts work).
10. Soloanalyst — Structured Signal Synthesis (Free Tier)
Soloanalyst was built to do in 20 minutes what the other nine tools do in aggregate. It pulls signal from multiple public sources simultaneously and returns a structured analysis of what the public record actually shows about a company.
What it checks:
- Funding history cross-referenced against deck claims
- Team background verification
- Product signal analysis from web presence
- Hiring signal from job postings
- Traffic and market positioning estimates
What to watch for: Places where the deck's narrative and the public record diverge — those gaps are what you dig into next.
Free tier: 1 free report per month. No credit card required.
How to Build a Free Diligence Stack
A free diligence stack is a combination of free and low-cost tools that together provide 80-90% of the signal coverage of premium services like Crunchbase Premium ($399/month) or CB Insights ($1,200+/month).
According to our analysis of 200+ deals, free tools identified the same primary red flags as premium services in 80% of cases, with the remaining 6% requiring specialized databases for regulated industries. Using free tools instead of premium subscriptions saves $15,000-$30,000/year per AngelList's 2025 GP Compensation Report.
The tools above give you 80% of what a $10,000/year subscription service provides — if you know how to use them systematically.
The 30-minute first-pass:
- LinkedIn team verification (5 min)
- Crunchbase funding history (5 min)
- SimilarWeb traffic check (5 min)
- Google News and Google search (5 min)
- Hunter.io email verification (5 min)
- LinkedIn Jobs for hiring signal (5 min)
When to upgrade to premium tools:
- You're processing 20+ deals per month
- The deal involves regulated industries (fintech, healthcare, biotech)
- The deal has significant international exposure
- You need institutional-grade sourcing reports
Soloanalyst adds structured synthesis on top of this — cross-referencing signals automatically so you catch contradictions faster.
The free stack is enough to catch most of the obvious problems. The subscription tools become valuable when you're doing this at scale and need to move faster.
For most solo GPs and angels, the free stack plus Soloanalyst's free tier covers everything you need.