# Customize a Service

URL: /products/service/customize · Id: `page:products/service/customize`

> What an Offer may change on its Service, what each buyer changes through its brief, and what never varies between two buyers of one Offer.

A [Service](/business/nouns/service) holds the default promise; each [Offer](/business/nouns/offer) may tighten it, never loosen it. Each buyer shapes its own job through its brief, and two buyers of one Offer always get the same promise.

## What an Offer changes
| An Offer sets | Example | Bound by |
| --- | --- | --- |
| Tighter contract terms | A rush audit with a 24-hour deadline | The Service's default contract: tighten only |
| `basis` | [Price](/business/nouns/price) per listing fixed (`output`) | The Service's assurance: `graded` checks support up to `output` |
| `payment` | A deposit at the order, the rest on acceptance | `onEarn`, `deposit`, `prepaid` or `milestones` |
| `agentBuyers` | Listed for buying agents | Needs `graded` assurance or an [Evaluator](/business/nouns/evaluator) that accepts |
| Its [Price](/business/nouns/price) | $99 for up to 1,000 listings | The contribution floor on [`Offer.publish`](/business/nouns/offer/publish) |

An Offer never names another done [Event](/business/nouns/event) than its Service's. The publish check refuses any Offer that breaks one of these bounds. A rush Offer that promises a refund on an unchecked step never goes live.

## What a buyer changes
A buyer shapes its job through its brief: the catalog, its size, its style guide and the turnaround it needs. The brief is the ceiling of what the [Order](/business/nouns/order) buys, and work beyond it goes on a new [Quote](/business/nouns/quote). [Intake forms](/products/service/intake-forms) shows how the brief is asked for.

A buyer that needs its own terms gets a private Offer, sold through a Quote. [Make a custom plan for one customer](/products/offers/make-a-custom-plan) is the guide.

## What never varies
[Experiments](/business/nouns/experiment) test copy, intake questions and Evaluators freely. They never vary a buyer's remedy, revisions, refund rights or acceptance window: two [Customers](/business/nouns/customer) buying the same Offer get the same promise.

A contract is versioned with its Offer. A new [Version](/business/nouns/version) applies to new Orders, and every placed Order keeps the terms it was bought under.

## What the builder changes
The builder changes the Service's steps, its checkers, its supply and its default contract in the product file. Each change builds a new Version, and each Offer published on it passes the same check.