| Mistake | Consequence | How to avoid it |
|---|---|---|
| Describing the solution instead of the problem | The provider builds what is written, not what is useful. The gap shows up at launch. | Start with the problem in numbers: hours lost, double entry, errors. |
| No list of screens | No firm quote: scoping at €3,000 to €6,000 excl. VAT becomes necessary. | List the screens of each journey, even as sketches. |
| Implicit business rules | Each rule discovered during the build stretches the timeline and is priced separately. | Write every rule with a worked example, exceptions included. |
| Putting everything in the V1 | The €6,000 to €25,000 MVP becomes a €25,000 to €60,000 complete app. | Fill in the out-of-scope section and reread it before sending. |
| An integration found along the way | €2,000 to €15,000 excl. VAT more per connection, and a shifted schedule. | List each tool, the data exchanged and the direction of each flow. |
| Offline mode “just in case” | The project moves into the €30,000 to €70,000 excl. VAT bracket, over 4 to 6 months. | Only ask for it if users really work without a network. |
| Payment added at the end | €2,000 to €5,000 excl. VAT for one-off charges, €4,000 to €10,000 for subscriptions, plus journeys to rework. | Choose the payment model in the integrations section. |
| Nothing about after launch | An app that does not keep up with iOS and Android releases ends up pulled from the stores. | Budget 8 to 12% of the build cost per year for upkeep. |
App specification template.
A complete template, free and with no email required, to describe your mobile app or your SaaS. Eleven sections, examples, and for each one what it changes to price and timeline. Filled in, it opens a build from €6,000 excl. VAT.
Fewer pages. Better apps.
Short answer
What is an app specification for?
A specification describes what your app must do, for whom, and within which limits. Its job is to get a firm price and a realistic timeline. To be priced, it must pin down three things: processes, business rules and the list of screens. With those three, a project starts at €6,000 excl. VAT at Krafter. Without them, a scoping phase of €3,000 to €6,000 excl. VAT produces them before development. The template below fits in fewer than ten pages.
- Purpose
- A firm price, a realistic timeline, a shared scope.
- Minimum content
- Processes, business rules, list of screens.
- Useful length
- Fewer than ten pages for a V1.
- Defined need
- Development from €6,000 excl. VAT.
- Need to shape
- Scoping at €3,000 to €6,000 excl. VAT on top.
- Why this floor
- An open source foundation, two senior partners who work with AI and review every line, no sales layer.
The template
The app specification template, in 11 sections.
Copy these sections into a document, answer the questions, attach your sketches. For each one: what to write, a short example, and what it changes to price and timeline. The examples follow a fictional case: a booking app for a network of 12 gyms.
Section 01
Context and goal
The problem to solve, with its numbers, and what must change once the app is live.
To write
- What problem are you solving, and what does it cost you today?
- What will prove, three months in, that the V1 worked?
- Who decides and who signs off on the project?
Example
Our 12 gyms handle bookings by phone and on a shared spreadsheet: 15 hours lost every week. Goal: 80% of bookings made in the app within three months.
Price and timeline
No direct cost, but everything follows from it. A clear goal lets you cut the rest without debate and keeps the V1 at the low end of the range.
Section 02
Users and roles
Who opens the app, in what context, and what each person is allowed to see or do.
To write
- How many profiles, and how many people per profile?
- Where do they use it: office, field, sofa?
- Who creates, edits, approves, deletes?
Example
Members (about 4,000): book and cancel. Coaches (40): open time slots, check attendance. Head office (3): manages the schedule and reports.
Price and timeline
Each role adds screens and permissions to test. Role management is one of the things that push an MVP above €6,000 excl. VAT.
Section 03
Journeys and screens
The list of screens and how the key journeys flow. A hand sketch is enough.
To write
- Which three to five journeys matter on day one?
- Which screens for each journey, and what information on each?
- What happens on an error or a cancellation?
Example
“Book a class” journey: home, gym schedule, class page, confirmation, reminder the day before. Five screens, one photographed sketch each.
Price and timeline
This is the section that sets the price. With a screen list, the quote is firm. Without it, €3,000 to €6,000 excl. VAT of scoping produces it before development.
Get your screens mocked upSection 04
Business rules
The calculations, conditions and approvals specific to your business, invisible on a mockup.
To write
- Which calculations: prices, deadlines, quotas, discounts?
- Which conditions block an action?
- Which exceptions exist, even rare ones?
Example
Free cancellation up to 4 hours before class, otherwise the session is used. Waiting list: the first person is notified and has 30 minutes to confirm.
Price and timeline
A written rule can be priced; a rule discovered mid-build stretches the timeline. Processes, rules and screens defined: the project starts at €6,000 excl. VAT.
Section 05
Data and content
What the app stores, where the data comes from, and who provides texts, photos and videos.
To write
- What information for each object: member, booking, class?
- Is there existing data to import, and in what format?
- Who writes the texts and supplies the images?
Example
Import of 4,000 member records from the current spreadsheet. Class descriptions and gym photos supplied by head office before launch.
Price and timeline
A data import is priced on the state of the source file. Late content delays the launch, not the development.
Section 06
Integrations
Every tool the app exchanges data with: payment, ERP, CRM, accounting, external APIs.
To write
- Which tools, and which data flows in which direction?
- Real time, or once a day?
- Does the tool have a documented API, and who has access?
Example
Online membership payment. New members pushed to the CRM every night. Visits read from the access control software.
Price and timeline
Each connection costs €2,000 to €15,000 excl. VAT depending on complexity. Payment adds €2,000 to €5,000 for one-off charges, €4,000 to €10,000 for subscriptions.
Integrations and APIsSection 07
Platforms
Target platforms: iOS, Android, web, or a PWA installed without going through the stores.
To write
- Are your users on iPhone, Android, desktop?
- Do you need the stores, or is installing from the browser enough?
- Is the back office on the web?
Example
Members and coaches on iOS and Android, through the stores. Head office on a web back office.
Price and timeline
Krafter builds iOS and Android in Flutter from a single codebase: one budget. A PWA costs less when the stores are not needed; Trottr, our field service SaaS, made that choice.
When to choose a PWASection 08
Constraints
What is not negotiable: offline mode, security, GDPR, hosting in France.
To write
- Do your users work without a network?
- Which personal data, and who can access it?
- Must the data stay in France, or on your own infrastructure?
Example
No offline mode. Personal data limited to name, email and phone. Hosting in France required by head office.
Price and timeline
Offline mode moves an app into the €30,000 to €70,000 excl. VAT bracket, over 4 to 6 months. Krafter hosts with a French provider, or on your own infrastructure.
Section 09
Out of scope for the V1
The written list of what the first version will not do. The most profitable section of the document.
To write
- What can wait three months without blocking anyone?
- Which requests have you already heard and set aside?
- Which profiles or cases stay out of scope?
Example
Out of V1: loyalty programme, online shop, English version, per-coach reports.
Price and timeline
Every exclusion is a debate avoided and a budget protected. It is often the gap between a €6,000 to €25,000 mobile MVP and a €25,000 to €60,000 complete app.
Section 10
Budget and deadline
Your budget, and the date that really matters, with the reason behind it.
To write
- What is the maximum budget for the V1?
- Which date cannot move, and why: season, trade show, fundraising?
- Who funds what comes next: revenue, a raise, your own funds?
Example
€20,000 excl. VAT for the V1. Live before the September rush, the peak sign-up period of the year.
Price and timeline
A stated budget lets us propose the right scope instead of an abstract quote. A SaaS MVP takes 4 to 8 weeks to build; a mobile MVP takes 8 to 12 weeks to reach the stores.
Section 11
After launch
Who keeps the app alive once it is live: updates, fixes, new features.
To write
- Who receives and sorts user feedback?
- How often should the product evolve?
- Whose name are the accounts, code and access in?
Example
Upkeep handled by the studio. New features on a time credit, paced by feedback from the gyms.
Price and timeline
Two levels. Upkeep: 8 to 12% of the build cost per year. New features: €700 to €1,100 excl. VAT per day, or on a time credit. At the end of the project, the Git repository, store and cloud accounts are in your name.
Variants
Mobile app, SaaS or business software: what changes.
The eleven sections apply to every project. Each type adds its own points.
Mobile app
- Developer accounts in your name: $99 a year at Apple, $25 one-off at Google.
- Notifications: which event triggers them, what they say, how often.
- Permissions requested on the phone (camera, location), and why each one.
- Store listings: name, description, screenshots, ready before submission.
On Melimelo, our Flutter app: more than 50 releases published, none rejected by Apple or Google.
Custom mobile appsSaaS
- Multi-tenancy: each customer in its own space, with its users and data.
- Subscriptions: plans, free trial, per-user or per-account pricing. Allow €4,000 to €10,000 excl. VAT for recurring payments.
- E-invoicing: French SMEs will have to issue electronic invoices from September 2027. If your SaaS bills its customers, write it down now.
- The back office: your customers, their subscriptions, support, key metrics.
Trottr, our field service SaaS, is sold by subscription with per-user licences.
Custom SaaS developmentBusiness software
- The current process, including workaround spreadsheets: they show how work really gets done.
- Approvals: who signs off on what, above which amount.
- Tools to connect (ERP, CRM, accounting), at €2,000 to €15,000 excl. VAT per connection.
- Importing existing data, and the format of the source files.
A simple internal tool runs from €6,000 to €15,000 excl. VAT, in 3 to 5 weeks.
Custom developmentQuotes
The mistakes that blow up a quote.
A quote rarely slips because of the code. It slips because of what was never written down. Eight common gaps, and what they cost.
Not ready yet
No specification yet? Two ways forward.
Scoping with Krafter
From €3,000 to €6,000 excl. VAT, on top of development. The two partners shape the thinking with you: processes, business rules, screens, V1 scope. At the end, this template is filled in, and your project is priced and dated.
The budget simulator
Eight questions, the studio’s real pricing grid, a range right away. Useful to check that your budget holds before writing anything.
Printable version
Print the template or save it as a PDF.
The button opens your browser’s print dialog: choose “Save as PDF” to keep a copy. For a Word file, copy the eleven headings and their questions.
FAQ
Your specification is ready, even halfway? Send it: a partner reads it and replies.
Tell us about your projectYour questions about app specifications.
Fewer than ten pages for a first version. Beyond that, the document describes details nobody has tested yet. What matters: processes, business rules and the list of screens. With those three, a project can be priced firmly and starts at €6,000 excl. VAT at Krafter.
Not necessarily. A list of screens with a hand sketch for each is enough to price the work. Clickable mockups help real users validate the journeys, but they can also come out of scoping, billed €3,000 to €6,000 excl. VAT when the need still has to be shaped.
They work together. The specification sets the context, roles, constraints and what stays out of the V1. User stories detail the journeys: “as a coach, I want to open a slot so that members can book”. Together, they are enough to price an MVP from €6,000 excl. VAT.
You, for the substance: nobody knows your business better. The provider then turns it into a priced, dated scope. At Krafter, the two partners, Fabien Maquin and François Pluchino, read your document and ask the questions, with no salesperson in between.
From €3,000 to €6,000 excl. VAT, on top of development, when the need still has to be shaped. Scoping produces what this template describes: processes, business rules, screens, V1 scope. If your specification already covers them, there is no scoping to pay for and development starts right away.
A range, yes; a firm price, no. The budget simulator gives an order of magnitude in 8 questions, and a first 30-minute video call with a partner refines it. A firm price needs a defined need, whether you bring it or scoping produces it.
This template is free on this page, with no email required. For a PDF, use the print button and choose “Save as PDF”. For Word or Google Docs, copy the eleven section headings and answer the questions under each. Substance matters more than layout.
A mobile MVP runs from €6,000 to €25,000 excl. VAT, a SaaS MVP from €6,000 to €30,000, a simple internal tool from €6,000 to €15,000. That floor comes from an open source foundation, two senior partners who work with AI and review every line, and no sales layer.
It is the basis of the quote: the V1 scope it describes is what gets priced and dated. A new request mid-project is priced separately, or replaces a planned feature to hold the date. A SaaS MVP scoped this way takes 4 to 8 weeks to build.
Two levels. Upkeep covers iOS and Android updates and security: 8 to 12% of the build cost per year. New features follow your roadmap, billed by time spent (€700 to €1,100 excl. VAT per day) or on a time credit. Both belong in the budget from the start.
Write it. Price it. → Ship it.
A 30-minute call with a founder. Answer within 24/48h. An unfinished specification is enough to start.