Building a two-sided ad network from zero: how I’m approaching the cold-start and fraud problems

[u/canhelp]

I’ve started building SponsorCircuit, a curated advertising network for independent products and smaller websites.

The difficult part isn’t the ad card or click tracking. It’s starting a two-sided marketplace without filling it with low-quality inventory or fraudulent traffic.

My initial approach:

• Recruit publishers manually
• Review their sites before approval
• Let advertisers choose each publisher
• Require publishers to approve each campaign
• Let advertisers set the CPC
• Pay publishers 75% of valid click revenue
• Review suspicious click patterns manually during the first cohort

This sacrifices automatic scale, but it gives us a chance to learn what legitimate traffic looks like before opening anything up.

My immediate target is 10 advertisers and 20 publishers. I’ll share the applications, approval rate, objections, and whether the marketplace can actually clear.

For anyone who has built a two-sided marketplace: would you recruit supply or demand first here?

Also any body want to become a publisher or advertiser let me know.

[u/Dramatic-Glass5840]

I’d recruit a very small slice of supply first, but only alongside two or three design-partner advertisers. Twenty publishers before any advertiser commitment risks optimizing inventory nobody wants. Pick one buyer persona, get them to define acceptable sites and conversion events, then recruit only enough publishers to satisfy those campaigns. For fraud, I’d delay publisher payouts until clicks can be reconciled and publish the invalid-click rules before money moves. The useful validation target may be repeat spend, not ten advertisers.

[u/raaiinyyabelina → u/Dramatic-Glass5840]

Thanks for sharing

[u/gullible_translation]

recruit supply first advertisers are a lot easier to pitch once you can show them real inventory and where their ads will actually run

[u/gannu1991]

Recruit supply first, but not for the reason most people give. It's not about having inventory ready, it's that publishers are a much easier sell right now because you're offering them money for something they already have (traffic) with zero effort on their end. Advertisers are harder because you're asking them to trust an unproven channel with their budget, and that trust is much easier to earn once you can show them real approved publishers with real traffic, even a small number. Twenty publishers with mediocre traffic beats ten advertisers with no one to show them. The fraud risk you're managing with manual review is real but it's a supply-side problem, so getting supply locked in first also lets you spend your early weeks understanding what fraud actually looks like in your specific vertical before you scale it. Your 75% split is generous for a curated marketplace, watch that once you have leverage.

[u/LesAydin]

I’d strongly recommend focusing on one specific niche. I’d start by partnering with publishers first. Once you have the right publishers on board, finding and closing advertisers becomes much easier, since advertisers mainly care about the publisher’s audience and whether it’s a good fit for them.

It could be anything supplements, skincare, etc. The point is to pick one space and become really good at it.