Nomad said in a tweet that it was "aware of the incident" and was looking into it, but provided no further details or the value of the theft.
PeckShield, a crypto analytics firm, told Reuters that $190 million in user cryptocurrencies, including ether and the stablecoin USDC, were stolen. Other blockchain researchers estimate the figure to be more than $150 million.
Based in San Francisco Nomad did not respond immediately to a request for comment.
According to a statement provided to cryptocurrency news outlet CoinDesk, the company has notified law enforcement and is working with blockchain forensics firms to identify the accounts involved and recover the funds.
Nomad, which raised $22 million in funding last week from investors including major US exchange Coinbase Global, creates software that connects various blockchains - the digital ledgers that underpin most cryptocurrencies.
The heist specifically targeted Nomad's "bridge," a tool that allows users to transfer tokens between blockchains.
Thefts, which have long plagued the crypto sector, have increasingly targeted blockchain bridges. According to the London-based blockchain analytics firm Elliptic, over $1 billion has been stolen from bridges so far in 2022.
Harmony, a U.S. crypto firm, announced in June that thieves stole approximately $100 million in tokens from its Horizon bridge product.
In March, hackers stole approximately $615 million in cryptocurrency from Ronin Bridge, which was used to transfer cryptocurrency into and out of the game Axie Infinity. The theft was linked to North Korean hackers, according to the US.
Nomad described itself as a "security-first" company that would keep users' money safe.
PeckShield stated that a small percentage of the coins were transferred to a "mixer," which hides the trail of crypto transactions, while the remaining $95 million was held in three other wallets.