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Apertio

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What Apertio is

Apertio is an open-source experimentation SDK for running A/B tests on web experiences without injecting JavaScript into a page. Built for the Next.js App Router, it resolves variants on the server or at the edge and includes them in server HTML on first paint. Engineers define typed slots with mandatory defaults and explicit bounds, then marketing can edit and test values within those limits without deploying code. Slots support text, enum, number, and boolean fields. A deterministic hash assigns variants, with the assignment retained in a cookie. The SDK is split into @apertio/core, @apertio/react, and @apertio/next; the core is MIT-licensed. Apertio says it avoids third-party scripts and DOM changes while preserving strict nonce-based CSP. The embedded schema is the security boundary, preventing out-of-bounds values. Only modeled slots are testable, so new surfaces still require engineering. North Shore Software Labs builds Apertio.

Who it suits

It suits engineering, marketing, and security teams working with the Next.js App Router. Teams needing server-side A/B testing and bounded variant values may find its slot model relevant.

What it does well

  • Open-source core with MIT license
  • Server-side and edge variant resolution
  • Typed slots with explicit bounds
  • Preserves strict nonce-based CSP
  • No third-party scripts or DOM injection

What to know first

  • Only modeled slots can be tested
  • Novel surfaces still require engineering
  • Self-hosting is only on the roadmap
  • Built for Next.js App Router

Verdict

Apertio provides bounded, server-rendered A/B testing for Next.js applications while avoiding client-side script injection. Its modeled-slot limitation is important when planning experiments on new surfaces.

Facts from Apertio's own pages

Assignment
Variant assignment uses a deterministic hash, and the assignment is kept in a cookie. · apertio.dev, 11 Oct 2026
CSP
The site says Apertio preserves strict nonce-based content security policies without requiring them to be loosened. · apertio.dev, 11 Oct 2026
Framework
Apertio is built for the Next.js App Router and provides core, React, and Next.js SDK packages. · apertio.dev, 11 Oct 2026
Getting started
The site offers a “Start free” signup link. · apertio.dev, 11 Oct 2026
How it works
Engineers define typed slots, and marketing can edit and test values within those bounds without deploying code. · apertio.dev, 11 Oct 2026
Intended teams
Apertio describes its workflow for engineering, marketing, and security teams. · apertio.dev, 11 Oct 2026
Intended users
The site describes Apertio as serving engineering, marketing, and security teams. · apertio.dev, 11 Oct 2026
License
The core is MIT-licensed. · apertio.dev, 11 Oct 2026
License and hosting
The core is MIT-licensed, and self-hosting is listed as being on the roadmap. · apertio.dev, 11 Oct 2026
Limit
Only modeled slots are testable; novel surfaces still require engineering. · apertio.dev, 11 Oct 2026
Limitation
Only modeled slots are testable, so novel surfaces still require engineering work. · apertio.dev, 11 Oct 2026
Maker
The site says Apertio is built by North Shore Software Labs. · apertio.dev, 11 Oct 2026
Product
Apertio is an open-source experimentation SDK for running A/B tests without injecting JavaScript into a page. · apertio.dev, 11 Oct 2026
Rendering
Variants resolve server-side or at the edge and are included in the server HTML on first paint. · apertio.dev, 11 Oct 2026
SDK packages
The SDK is layered into @apertio/core, @apertio/react, and @apertio/next. · apertio.dev, 11 Oct 2026
Security
The site says Apertio does not inject third-party scripts or touch the DOM, and that its bounded variant data keeps a strict nonce-based CSP intact. · apertio.dev, 11 Oct 2026
Security boundary
The site says the schema embedded in the running app is the security boundary and the platform cannot make the app render out-of-bounds values. · apertio.dev, 11 Oct 2026
Self-hosting
Self-hosting is listed as being on the roadmap. · apertio.dev, 11 Oct 2026
Server rendering
Variants resolve on the server or at the edge and are included in the server HTML on first paint. · apertio.dev, 11 Oct 2026
Slot types
Slots can be text, enum, number, or boolean fields with a required default and explicit bounds. · apertio.dev, 11 Oct 2026
Supported framework
Apertio is built for the Next.js App Router. · apertio.dev, 11 Oct 2026
Supported slot types
Slots can be text, enum, number, or boolean fields with a mandatory default and explicit bounds. · apertio.dev, 11 Oct 2026

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