Fixed-price app development, explained.

Most software is sold one of two ways. Time and materials means you pay for the hours worked: flexible, but the total is only known at the end, and a project that runs long costs you more. Fixed price means you agree a scope and one price for it up front: the total is known before anything starts, and the builder carries the risk of the work taking longer.

Fixed prices are rarer because estimating software is hard, and whoever offers one has to absorb their own mistakes. That is exactly why it is worth having when you are paying for the work yourself.

A fixed price is only as good as the scope it is attached to. Before you accept one, check that it covers:

• a written scope that says what will be built, in terms you understand;
• everything needed to deliver that scope, not only the coding: planning, review, testing and the release;
• fixing what does not work as agreed, without a new bill;
• what happens when the work costs the builder more than they expected.

Changes of mind. A fixed price is for a fixed scope. Asking for something the scope did not include, such as a new feature or a different behaviour, is new work, and it should be priced as new work, with your approval, before it starts.

Running the product. Hosting and keeping software running after release is an ongoing cost, separate from building it. Be wary of a price that folds the two together, because you cannot tell what you are paying for.

Other companies' services. A payments provider, for example, bills you directly at its own prices.

Before any work starts, you see the scope and one price for it, and the build begins only when you accept. That price covers planning, engineering, code review, testing and preparing the release, with the AI models the agents run on included. If a review or a test finds something that does not work as agreed, fixing it is part of the same price, however many attempts it takes.

If the build costs more than quoted, the price you approved does not change: higher costs on our side are ours to absorb. A change of scope gets its own quote, and nothing changes until you approve it. The delivery date is a forecast, not a promise; the commitment is the price.

Running a released product is a separate monthly price, in tiers that depend on the product's scope, performance and scale. Every build quote names the tier its product falls under, so you see the running cost before you approve the build. A database, user sign-in and email come with the 19 Agents stack, inside the running price. The pricing page has the details.

The beta does not charge you money; the terms are shared on admission, before you build anything. Any figures you see on this site are illustrative examples, and a forecast during planning is an estimate. The number that counts is the fixed quote for a specific scope.

• The beta is closed, and admission is gradual. It is not offered in the United Kingdom.
• Every product starts from a new idea. Bringing code you already have comes after the beta.
• The beta is for building and testing: it does not include collecting personal data about real customers or users, or connecting a production database.
• Not every type of application or business requirement is supported yet.