Slapp

Slapp is a mobile-first social app for Iceland, in Icelandic only, built and run by Vestra AI ehf. The only way to sign in is Kenni, the Icelandic electronic ID, so every user maps to a kennitala and a verified birthday.

The core loop is a friends-plus-discovery feed of posts with up to 20 images, video up to 600 seconds, polls, stickers and attached music clips. Around it sit daily stories, direct and group messaging with per-conversation encryption, a groups hub that also hosts a consumer marketplace and a rental market, an 18+ dating tab, events, multi-author pages including automated ones, a set of games, seasonal modes, a business-offer marketplace, and a subscription called Slapp+.

There is no email-and-password path. Better Auth runs inside Convex with one OAuth provider, Kenni, using OIDC discovery and PKCE. At sign-up the backend encrypts the full kennitala, keeps the first six digits as a birthday key, and assigns a sequential member number. Because every birthday is real, age gates are enforced on the server: 13 to join, 18 for dating and the marketplaces, and a feed variant per age band. The member number appears in onboarding and is printed on the member tee sold through the shop.

Two developers built and run it. The first real commit is from 2 December 2025, version 1.0.0 shipped on 10 January 2026, and the current version, 2.6.0, shipped on 28 August 2026. By September 2026 the app had more than 22,000 verified users, over 5% of Iceland's population, with no paid marketing. The chapters below describe the system in detail.

Where it runs

• Slapp
• Expo
• React Native
• Next.js
• Convex
• Cloudflare
• Shopify
• Printful

Key numbers

Repository counts were verified against the working tree at commit 162a2bfd on 2 September 2026 and exclude generated code and node_modules. The user count is from September 2026.

In the news

The launch in early 2026 was covered by the Icelandic press. Each piece is listed with its title as published, an English translation and a line on what it covers.

1. Morgunblaðið, Sunnudagsblað, 21 February 2026

   „Flestir komu inn á síðustu dögum“

   Most of them joined in the last few days

   Ásdís Ásgeirsdóttir talks to both founders; the full interview ran in the Sunday paper. At the time of writing 8,296 people had joined, most of them in the days before.

2. K100, Síðdegisþátturinn, 19 February 2026

   Nýr íslenskur samfélagsmiðill

   A new Icelandic social network

   Radio interview. Þór Bæring talks to Bjarki in the afternoon show about the launch.

3. Vísir and Sýn, evening news, 16 February 2026

   Nýr samfélagsmiðill bara fyrir íslenskt samfélag

   A new social network just for Icelandic society

   Kristján on why every account is a real person signed in with electronic ID, and on the party button, which tells your friends you are out. Sýn's evening news covered Slapp the same evening; Vísir's video announcing the segment is on Facebook.

4. Viðskiptablaðið, 14 February 2026

   Nýr íslenskur samfélagsmiðill

   A new Icelandic social network

   Helgi Steinar Gunnlaugsson on the launch: sign-in with electronic ID, no advertising, and the sports network the founders considered building first.

5. Bylgjan, Reykjavík síðdegis, 12 February 2026

   Nýr íslenskur samfélagsmiðill með engum auglýsingum

   A new Icelandic social network with no advertising

   A nine-minute radio interview with Kristján about the app and running it without ads.

The case study

Eight chapters in reading order. Each one ends with a link to the next.

1. 2IdentityThe eID identity model: no passwords, a verified birthday, and a member number.
2. 3ArchitectureThe Convex backend, the five clients, and how data moves between them.
3. 4ProductThe feature map and every major surface of the app.
4. 5Machine learningEvery model is logistic regression or a self-trained embedding, trained inside Convex.
5. 5.1Feed rankerRetrieval by fan-out, then a six-head logistic regression over the top 80 candidates.
6. 5.2EmbeddingsTaste vectors from item2vec and graph vectors from Node2Vec, both 128 dimensions.
7. 5.3Friend suggestionsCandidate sources, the friend ranker, Gumbel noise, and the closeness score underneath.
8. 5.4Growth modelsHook signals, the notification ranker, churn risk, post propensity and retention importance.
9. 5.5DatingElo with weekly replay, the power score, and the daily pick.
10. 6MonetisationSlapp+, Tilboð offer slots, loyalty clubs, invoices and the member tee.
11. 7ScaleRepository facts, commits per month, the release timeline, and size by area.