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Custom Software · Nationwide

Custom software, built around how your company actually works.

We design and build internal systems, customer portals, web apps, mobile apps and the connectors that put your product inside Claude and ChatGPT, for companies across the United States. One set package price, agreed in writing before we build, and the code, the domain and every account are yours.

Tell Us What to BuildFor Large Companies

A person reads every inquiry and answers inside one business day.

Painting: at a lantern-lit beachside dinner, Mr. Mustard shows friends a tablet of website layouts while Mrs. Mustard raises a glass, the kids wave sparklers and a lit-up yacht sits on the water behind
What we build

The software your teams and your customers actually use.

  1. Internal systems and dashboards.

    The spreadsheet three teams share, the approval that lives in someone’s inbox, the report somebody rebuilds every Monday. We turn it into one system your people sign in to, with roles, a record of who changed what, and the numbers live.

  2. Customer portals and web apps.

    A place your customers sign in to order, book, pay, upload, sign and see where things stand, so your team stops answering the same email all day.

  3. Mobile apps.

    iOS and Android apps built with Expo from one codebase, with sign-in, payments and push notifications, taken through App Store and Google Play review.

  4. Integrations.

    Stripe, Shopify, Google, Twilio and the systems you already pay for, wired together so an order, a lead or a payment moves on its own and lands in the right place once.

  5. Agent systems, with people in charge.

    Agents that read, sort, draft and follow up across your tools, built so a person approves anything that sends, charges or changes a record.

  6. Your product inside Claude and ChatGPT.

    Connectors (MCP servers) that put a software company’s product inside Claude and ChatGPT, each customer signing in to their own account. Nine of our own connectors are listed in Anthropic’s Claude directory.

Idea to Product

Four set packages, from the plan to the keys.

Start at the step you are on. Each one is its own set price, agreed in writing, and each ends with something you own.

How an Engagement Runs

  1. Scope and Sequence

    The idea becomes a specified, sequenced build plan: what gets built, in what order, what is out, and the dates.

  2. Build and Ship

    The product gets built and put in front of real users, on a live link from the first week, with a written update every week.

  3. Launch

    It goes to market with the system around it in place: the site, the onboarding, the email, the search work and the measurement.

  4. Hand Off

    The repository, the hosting, the database, every account and the operating knowledge transfer to your team, documented.

What your buyers will ask

The answers, before your procurement team asks.

Price
One set package price for the scope, in writing before we build, and it does not move. Changes to what we built are included.
Ownership
The repository, the domain and every account are in your company’s name from day one.
Your requirements
Send your vendor, security and accessibility requirements with your inquiry, and the proposal answers each one in writing.
Accessibility
Built to WCAG 2.2 AA, checked with axe and walked by keyboard and screen reader before launch.
Pace
An answer inside one business day, a proposal within 48 hours of the working session, and a build measured in days to weeks, fixed in the proposal.
The stack
Next.js and TypeScript, Postgres on Supabase, Vercel and Stripe by default, and Expo for iOS and Android.
The work

Some of the software we have built.

See Some of Our Projects
Questions

Custom software, answered plainly.

Who builds custom software for companies across the US?

We do. Modern Mustard Seed designs and builds custom software for companies of every size across the United States: internal systems, customer portals, web apps, mobile apps, integrations and the connectors that put a product inside Claude and ChatGPT. Every build is one set package price agreed in writing before work starts, changes to what we built are included, and the code, the domain and every account are yours.

How much does custom software cost?

One set package price for the scope. It comes in a private proposal within 48 hours of one working session, with the milestones, the dates and an explicit list of what is out, so the number does not move. Changes to what we built are always included.

How long does a custom software build take?

Days to weeks, fixed in the proposal before work starts. You get a live link the moment there is something to look at and a written update every week, so you see the build happen instead of waiting for a reveal.

Do you work with large companies?

Yes. We build for companies of every size, from an owner-run business to a large company with a procurement process. Send your vendor, security and accessibility requirements with your inquiry, and the proposal answers each one in writing.

Who owns the code?

You do. The repository, the domain, the hosting and the database are in your company’s name from the first day. We run and improve it for you after launch, and if you ever want to run it in house, Hand Off transfers everything with the documentation.

Can you put our software inside Claude and ChatGPT?

Yes. We build connectors (MCP servers) that put a software company’s product inside Claude and ChatGPT, with each customer signing in to their own account and an approval step before anything writes. Nine of our own connectors are listed in Anthropic’s Claude directory.

Do you build outside Montana?

Yes. Our studio is in Kalispell, Montana, and we build for companies in every US state.

Start here

Tell us what your company needs built.

The business, the problem, and what a good outcome looks like. Sarah Scarano, our founder, reads every inquiry, and the working session that follows is where the plan takes shape.

Write to UsCustom Software in Montana