The basics
A SAFE — Simple Agreement for Future Equity — is a contract in which an investor provides money now in exchange for the right to receive equity in the future, typically at a priced funding round. SAFEs were created by Y Combinator in 2013 as a faster, cheaper alternative to convertible notes. Unlike convertible notes, SAFEs carry no interest rate and have no maturity date — they are not debt instruments.
SAFEs have become dominant in early-stage fundraising. Data from Carta shows that in Q1 2025, SAFEs accounted for 90% of all pre-seed deals and 64% of seed-stage deals in the US. Outside the US, adoption is growing, particularly in Europe, where SAFEs are increasingly used alongside local instruments.
How a SAFE converts
The SAFE converts into equity when a trigger event occurs. The standard triggers are: a priced equity financing round (most common), an acquisition of the company, or an IPO. At conversion, the investor receives shares at a price determined by the SAFE's terms — typically better than what new investors pay in the priced round.
The four key terms
Valuation cap: the maximum company valuation at which the SAFE converts, regardless of the actual round valuation. If you raise a $10M valuation cap SAFE and later close a Series A at a $20M pre-money valuation, the SAFE holder converts as if the valuation were $10M — receiving twice as many shares as new investors for the same price. This is the investor's upside protection. Approximately 72% of SAFEs issued in 2025 used a valuation cap with no discount.
Discount rate: the percentage reduction from the next round's share price at which the SAFE converts. A 20% discount means the SAFE holder pays 80 cents for every dollar of share price. Usually used as an alternative (or addition) to a valuation cap.
MFN (Most Favoured Nation) clause: if the company later issues SAFEs on better terms, the existing SAFE holder automatically gets those better terms. Common in uncapped SAFEs.
Pro-rata rights: the right of the SAFE holder to invest additional money in the next priced round to maintain their ownership percentage. Not standard in all SAFEs — negotiate explicitly if important.
Post-money vs pre-money SAFEs
Y Combinator shifted to post-money SAFEs in 2018. The difference is material: in a post-money SAFE, the valuation cap is calculated after all SAFEs are included in the cap table, giving investors a clearer picture of their exact ownership at conversion. Pre-money SAFEs can lead to unexpected dilution when multiple SAFEs convert simultaneously. Most new SAFEs use the post-money structure.
When a SAFE makes sense — and when it doesn't
SAFEs are well suited for pre-seed and seed rounds where speed matters and both sides want to avoid the negotiation overhead of a priced round. They work best when the amount raised is meaningful to the company but not so large that precise ownership matters immediately.
SAFEs become problematic when: a company issues many SAFEs over time without tracking cumulative dilution; investors stack multiple SAFEs with different caps, creating a complex conversion waterfall; or when raising in jurisdictions where SAFE enforceability is untested. For non-US founders, the legal validity of a SAFE under local law should be verified before use.
Alternatives
For founders outside the US, convertible notes (loan agreements with equity conversion rights) are often more familiar to local investors and banks. Some European jurisdictions have developed local equivalents. The choice depends on investor expectations in your ecosystem and the legal infrastructure available.