# The Three Implementation Tiers
Source: https://humanspark.ai/frameworks/three-implementation-tiers/

*Three ways to add AI to a process - very different cost, speed and risk.*

**When to use:** Deciding how to build, once you know what to build. Most first pilots are Tier 1.

Higher rung = more risk, cost & customisation ↑

Custom R&D

Building bespoke on your private data.

Where the failure rate lives.

Retrofit

Switching on AI features in software you already own.

sweet spot

Toolkit

Off-the-shelf tools - turning a key. Lowest risk, monthly billing.

> **Not to be confused with:** Not [the Three Ways of Working](https://humanspark.ai/frameworks/three-ways-of-working/): the Tiers say how you source AI; the Ways say how you work with it once it's there.