a16z CSX (Crypto Startup Accelerator)

a16z CSX (Crypto Startup Accelerator) is a16z crypto's intensive, in-person program for early-stage startups building with blockchain technologies. It connects founders with capital, a16z crypto's investing and operating teams, industry experts and a cohort of other web3 teams, and a16z crypto invests a minimum of $500,000 in each accepted company.

It started in February 2020 as Crypto Startup School, a seven-week program whose 40 founders went on to build companies such as Phantom, Flashbots, Goldfinch and Notional Finance; a16z says that cohort raised over $300M and its lectures were viewed over 1M times. In October 2022 a16z crypto relaunched it as a full accelerator, and it was later renamed CSX. In 2024 it ran twice for the first time: Spring 2024 in London (25 startups, 10 weeks) and Fall 2024 in New York City (21 startups, 8 weeks). The fourth accelerator cohort, CSX 04, ran in San Francisco from April to June 2025 and ended with a Demo Day.

Each week focuses on a pillar of company building, such as research and engineering, marketing and social, go-to-market and people, through workshops and one-on-one sessions. No cohort has been announced since CSX 04, and the CSX page now shows no application; a16z's early-stage accelerator activity runs through a16z speedrun.

CSX backs early-stage teams building across the crypto stack, including infrastructure, DeFi, consumer apps, payments, games, developer tools, DePIN and AI x crypto, with founders from around the world.

Applicants should have a clear web3 product vision and be prepared to commit to the in-person program. Technical founders are preferred, and startups across various crypto verticals are encouraged to apply.

Early-stage startups building with blockchain technologies, from any country. Founders had to attend the in-person program in the host city (London, New York City or San Francisco in recent cohorts). Cohorts spanned infrastructure, DeFi, consumer apps, payments, games, dev tools, DePIN and AI.

Past cohorts used an online application with a fixed deadline (for example, February 7, 2025 for CSX 04 and March 29, 2024 for Fall 2024). a16z crypto described the field as very competitive, with applications from across the world. No application is open now.

• Minimum $500,000 investment from a16z crypto.
• Weekly modules on product-market fit, business models, web3 infrastructure, decentralization and tokenization, go-to-market, brand, hiring, fundraising and legal and regulatory issues.
• Workshops and one-on-one time with a16z crypto's investing, engineering, research, marketing and policy specialists.
• A cohort of other web3 teams and the a16z network.
• A Demo Day with investors and crypto executives.
• A public resource library at a16zcrypto.com/accelerator/library.

• Feb 2020: first Crypto Startup School (7 weeks, 40 founders).
• Oct 17, 2022: relaunched as a full accelerator.
• Late March 2024: Spring 2024 cohort starts in London (25 startups, 10 weeks).
• Sep to Nov 2024: Fall 2024 cohort, New York City (21 startups, 8 weeks, Demo Day in November).
• Apr to Jun 2025: CSX 04, San Francisco (applications closed Feb 7, 2025).
• No cohort announced since.

The 2020 Crypto Startup School cohort produced Phantom, Flashbots, Goldfinch, Notional Finance, Teller, Afriex and FanCraze, and a16z says those founders raised over $300M. Later cohorts include Neynar, MagicBlock, Sablier, NEBRA Labs and OpenTrade (Spring 2024), Anera Labs and Blocksense (Fall 2024), and Ambient, Cambrian, Inco Network, Miden and ZAR (CSX 04).