This is Vol. 1 of a log I’m going to keep publishing until YonoSIM APIhits its first meaningful cohort of paying partners. The plan I actually followed for the last 60 days — ship the API, ship 45 SEO pages across 7 audience pillars, then go quiet and wait — is the plan that produced zero signups. So the plan has to change, and the change starts here.

What YonoSIM API is, in one paragraph

A public eSIM provisioning API. You pay the published retail rate — the same rate a traveler pays on yonosim.com, exposed in the API — bundle it inside your product (travel app, hotel checkout, insurance flow, tour operator itinerary, IoT device), and your customer never has to leave your checkout to buy connectivity. A sk_test_*sandbox key with $10 of test credit lands in your inbox on signup. No NDA, no minimum, no sales call. It’s live at api.yonosim.com.

Between Airalo Partners (NDA + a 2-6 week sales cycle) and rolling your own against raw eSIMAccess wholesale (no support, no billing, no white-label). If that in-between space is a business, YonoSIM API is trying to be the Stripe of it.

Numbers I’m not hiding

Pulled straight from Postgres this morning:

• 17 commits on yonosim-api since the v0.1 mock-mode drop
• 2 Fly machines serving api.yonosim.com in iad
• 0 developer waitlist signups all-time
• 0 named paying API customers
• 1 physical-kiosk deployment running against the same infrastructure in production
• 116 consumer eSIM orders on the yonosim.com side since 2022 (58 in the last 90 days) — that funds the runway

Consumer revenue is roughly $350 per 28 days right now. Target is $20k MRR. So this is not a “post-launch cruising toward IPO” log. This is a “the plumbing works, the pitch is sharp, nobody’s showed up yet, here’s what we’re doing about it” log.

Why I’m publishing this

Because the plan I actually followed for the last 60 days produced 0 signups, and I ran a marketing council on the situation this week that came back with the same diagnosis five different ways: the surface is fine, the distribution is missing. Godin’s version was the bluntest — the 45 SEO pages are broadcasting into a void because you haven’t earned permission from a single reader.

This log is the permission-earning move. Weekly-ish. Real numbers, real conversations, real wholesale pricing math with the supplier. In my voice, not YonoSIM the platform’s. If it stops being interesting, I’ll stop writing it — but the alternative was another quiet quarter.

Three things I fixed this week

1. Killed the “Request early access” waitlist gate on /developers. The form had already been auto-issuing a sandbox key + $10 credit on submit since PR #527. The copy just didn’t say so — it still read like a “prove you belong here” ledger. Now the CTA is “Get a sandbox key” and the button says “Email me the sandbox key.” One-hour change, but the site was fighting its own positioning until I made it.

2. Rewrote the hero to name the actual alternatives. Old subhead: “between raw-wholesale APIs and retail resellers with no partner program” — vague, forgettable. New subhead: “without an Airalo Partners NDA, a Twilio-Super-SIM contract, or wiring raw eSIMAccess yourself.” Naming the competitor by name is a Sales Pitch move — your buyer already has an evaluation matrix in their head; the pitch that lands is the one that walks their matrix.

3. Started this log. Which is the fix that’s supposed to compound.

The wholesale math, since someone always asks

Every eSIM sold through YonoSIM (consumer or API) runs on the same wholesale supply. We buy from two suppliers now — the legacy one (eSIMAccess, since 2022) and a second one we added a sandbox integration for in August 2026 (TGT / Turbo Global Telecom). Provider-agnostic aggregator inside src/upstream/client.ts so store.ts doesn’t care which one fulfilled.

Wholesale margins are thin — this isn’t a “buy for a dollar, sell for ten” business. On a typical 5 GB Japan plan the wholesale cost is somewhere in the $2.50–$3.50 range and the published retail is $8.99. That’s the “one rate” you get through the API. The volume rebate at ~$10k+/mo is a private per-key rebate against retail, not a public tier ladder — the reason it’s private is that we can’t cross-subsidize a large partner from the retail rate without punishing the retail buyer.

If you’re building on us and you’d rather see raw wholesale, that’s what Airalo Partners’ NDA covers. If you don’t want to sign the NDA, the retail rate + volume rebate is the deal.

What I’m trying next week

Three things, prioritized:

1. /business hero rewrite — same Sales Pitch structure I just applied to /developers, so the two front doors say the same thing.
2. Find three real API prospects in warm channels — no cold outreach (never), just showing up in the rooms where the right people already are (Indie Hackers travel/tour launches, HN threads about eSIM/roaming APIs, X build-in-public founders whose product could use eSIM).
3. Vol. 2 of this log. Whether the score is 0/3, 1/3, or 3/3 by then. The score is the log.

How to reach me / what I want

• Sandbox key: yonosim.com/developers — instant, no card, no call.
• Playground: api.yonosim.com/docs — shared demo key already loaded.
• Reply to this log with what you’d want to see in Vol. 2. Also: if you’re building a travel-adjacent product and eSIM is on your list, I’d like to hear about it — I’ll ship you free live-mode credits in exchange for a call about the integration.

— Yoni · @YonoSIM · #YouOnlyNeedOneSIM

Common questions

Originally published on www.yonosim.com/en/blog/building-yonosim-api-in-the-open-vol-1 · YonoSIM — You Only Need One SIM