ernd vs Mercury for AI spend

The short answer

If you bank with Mercury and AI isn't a big bill, IO is hard to argue with. It pays 1.5% cash back on everything, and it's right there in your account. The ernd card also pays 1.5% outside AI, so on that spend it has no rate advantage.

The difference is on AI vendors, where the ernd card pays 4% back. If those bills are large, it can earn its place as a second card.

Side by side

Compared	Mercury	ernd
Back on AI vendors	1.5% cash back	4% back
Back on everything else	1.5% cash back	1.5% back
Annual fee	None	None
Who it's open to	Mercury's IO page says to open a Mercury account first. Its card agreement says a deposit account isn't required	Live for US companies. Request the card at app.ernd.ai

Where Mercury wins

• If you bank with Mercury, there's no separate application for IO, and new customers with lower balances can start using it right away on daily repayment terms. Source
• Cash back lands in your account automatically once you pay your balance. Source
• 1.5% with no categories to think about, on every purchase. Source
• Your banking, card and transactions are in one place, with AI coding your expenses. Source

Where ernd fits

• A higher rate on the AI line. The ernd card pays 4% back on AI vendor spend, OpenAI and Anthropic included, against 1.5% cash back on IO.
• ernd's partners set their own rates and perks: Wafer gives 10% back on inference, Hopper 8% back and a free first month, Agent 37 4% back, Conifer 6% back, and Superserve and AgentPhone 5% back. Trace's Startup pen test plan is $1,500 instead of $4,000, and Firecrawl doubles usage limits. OpenAI and Anthropic aren't ernd partners.
• You don't have to move your banking. Keep your current bank account and use the ernd card for your AI vendors.

The partners page lists ernd's partners. To see Mercury next to Amex, Chase, Slash, Dash.fi and Rho, go to the full comparison. For caps and merchant categories on OpenAI and Anthropic bills, read our guide to the best credit cards for those bills.

An example

Say you spend $20,000 a month on AI vendors. IO pays $300 a month in cash back on that, and the ernd card pays $800 at 4%. If your AI bill is small, the gap may not be worth carrying a second card.

Questions

Is Mercury IO a charge card?

Yes. Mercury says IO is a charge card, so you pay the full balance every pay period. New customers with lower balances start on daily repayment, and Mercury offers 30-day terms once balances reach $15K.

Do I need a Mercury account to use IO?

In practice, yes. Mercury's IO page says you first need a Mercury account, and it sets your limit from your balances there. Its card agreement says a deposit account isn't required, so ask Mercury if you'd rather bank elsewhere.

Can I use ernd and Mercury together?

Yes. You can keep banking at Mercury and put only your AI vendors on the ernd card.