---
title: "Microsoft Dynamics 365 Development Services"
canonical_url: https://msdynamicsguys.com/services/dynamics-365-development/
description: "MS Dynamics Guys builds Microsoft Dynamics 365 extensions, Dataverse plug-ins and AL apps, with code review, tests and documented handover."
publisher: "MS Dynamics Guys"
last_modified: 2026-10-14
---

# Microsoft Dynamics 365 development services your team can maintain

> **Short answer:** MS Dynamics Guys builds and extends Microsoft Dynamics 365 applications when standard configuration cannot do the job. We add business logic, connect systems and replace fragile custom code. Depending on the app, the work uses Dataverse, C# and Power Platform components for Sales and Customer Service, or AL for Business Central. We confirm the product, scope and delivery model before we estimate.

**At a glance**

- **Apps:** Sales and Customer Service on Dataverse; Business Central online and on-premises
- **Typical work:** Extensions, business logic, reports and integration endpoints
- **You receive:** Code in your repository, automated tests, release notes and handover documentation
- **Delivery:** A scoped project, or developers who work inside your team

[Discuss a development project](https://msdynamicsguys.com/contact/#intent=project&service=S01) · [Add a developer to your team](https://msdynamicsguys.com/hire/)

## When does Microsoft Dynamics 365 need custom development?

Most Microsoft Dynamics 365 requirements start as configuration: fields, forms, views, business rules, security roles and Power Automate flows. Custom development is justified when one of these situations applies:

- A rule must run inside the transaction on every save, whatever the entry point: a form, an import or an API call.
- A calculation or validation is too complex, or too slow, for low-code tools.
- Users need an interface control that standard forms cannot provide.
- Another system needs a stable, versioned application programming interface (API) instead of direct access to tables.
- Existing custom code breaks during updates, blocks releases or has no tests.

If none of these apply, we say so. Configuration is cheaper to run and easier to hand over than code.

## What development means in each Microsoft Dynamics 365 app

Each product has its own language, platform limits and release rules. A developer who is strong in one is not automatically productive in another.

**Development scope by Microsoft Dynamics 365 product**

| Product | Platform and language | Typical MS Dynamics Guys work | Limits to plan for |
|---|---|---|---|
| Sales, Customer Service, Field Service | Microsoft Dataverse; C# plug-ins on .NET Framework; TypeScript for PCF (Power Apps component framework) controls | Plug-ins, custom APIs, PCF controls, model-driven app changes, security roles, managed solutions | No direct database access. Code must stay within Dataverse service protection limits and solution layering. |
| Business Central | AL extensions built in Visual Studio Code, online or on-premises | Table and page extensions, event subscribers, reports, API pages, automated tests, update checks | Online has no direct database access and no .NET interop; designs that need them require on-premises. |
| Power Platform around Microsoft Dynamics 365 | Power Apps, Power Automate and Dataverse | Canvas and model-driven apps, flows with error handling, environment and ALM (application lifecycle management) setup | Licenses decide which connectors and capacity you can use. We check them before design. |
| Finance and Supply Chain Management | X++ extensions and data entities | Extensions, event handlers, data entities, integration endpoints, release testing | Overlayering is not supported; all changes are extensions that must survive Microsoft service updates. |

> **Configuration first**
>
> A custom build is not always needed. MS Dynamics Guys first checks the standard feature, existing Microsoft Marketplace apps and available connectors. We recommend code only when those options cannot meet the requirement at an acceptable cost and maintenance level. When an existing product fits better than a build, we tell you which one and why.
>
> For a request to add an AI agent, use the [Copilot Studio scope and evaluation plan](https://msdynamicsguys.com/power-platform/copilot-studio-consulting/) before choosing a build. It asks which workflow the agent may handle, which data and tools it may use, and who receives cases it cannot resolve.

## How MS Dynamics Guys delivers a development project

The steps stay the same across products. The tools change: solutions and pipelines for Dataverse, app packages and test codeunits for Business Central.

1. **Confirm the requirement and the product:** We review the process, the app and version, and any existing customizations. We agree what success looks like and how it will be tested.
2. **Technical design:** We write a short design: components, data touched, security, failure handling and how the change is released. You approve it before build starts.
3. **Build in your repository:** Code goes into your source control from the first commit. You keep the full history, whoever maintains it later.
4. **Review and automated tests:** A second engineer reviews every change. Business logic ships with automated tests where the platform supports them.
5. **Test outside production:** Changes are deployed to a sandbox or test environment first. Your users test against agreed scenarios before release.
6. **Release and hand over:** We release through an agreed process, record what changed and hand over notes your team or another partner can use.

The full delivery model, including environments and acceptance, is on [how we work](https://msdynamicsguys.com/how-we-work/).

## Who does what on a development project

**Responsibilities on a typical development project**

| Task | Your team | MS Dynamics Guys |
|---|---|---|
| Business requirements and priorities | Owns and approves | Asks questions, flags conflicts and gaps |
| Environment access and source control | Grants access; owns the repository | Works within the access granted |
| Technical design | Reviews and approves | Writes and maintains it |
| Code, review and automated tests | Optional review by your developers | Delivers all three |
| User acceptance testing | Runs tests and signs off | Prepares test scenarios and fixes defects |
| Production release | Approves the release | Packages and deploys, or supports your release team |
| Microsoft licenses and capacity | Buys and manages them | Tells you what the design needs |
| Handover | Names who will own the code | Documents and walks through it |

## Should MS Dynamics Guys own the work, or should a developer join your team?

Both routes can produce the same code. They differ in who plans and directs the work, and in what your team must supply.

**A development project or a developer in your team: when each fits and what your team supplies**

| Your situation | Better fit | What your team supplies |
|---|---|---|
| You can describe the result and its acceptance criteria before work starts, for example one integration endpoint or one approval rule | A scoped development project. MS Dynamics Guys designs, builds, tests and hands over the agreed change. | Requirements, scope approval, user acceptance testing and the release decision |
| Plug-in fixes, form scripts and small custom APIs for your customer relationship management (CRM) apps arrive every sprint, and your lead often reorders them | [A Microsoft Dynamics 365 CRM developer](https://msdynamicsguys.com/hire/dynamics-365-crm-developers/) who joins your team | A lead who sets priorities, a decision on who reviews code, and accounts in your tenant |
| Your own technical lead plans the AL extension work, and the extensions must be tested again before each Business Central update | [A Business Central developer](https://msdynamicsguys.com/hire/business-central-developers/) who joins your team | A technical lead who sets priorities and accepts each change, plus sandbox and repository access |
| Business users built canvas or model-driven apps that now need a developer to finish, secure and maintain them | [A Power Apps developer](https://msdynamicsguys.com/hire/power-apps-developers/) who joins your team | An app owner who decides the scope, and access to your environments and solutions |

A developer in your team works under your direction and in your tools. Your lead sets priorities and accepts finished items. If you need MS Dynamics Guys to plan and deliver a defined change instead, discuss a development project. Your team still owns the business requirements and release approval.

Every developer we introduce has passed our [technical screening](https://msdynamicsguys.com/how-we-work/technical-screening/). You interview each one and decide who joins. [Staff augmentation or project delivery](https://msdynamicsguys.com/resources/dynamics-365-staff-augmentation-vs-project-delivery/) compares the two models in more depth.

## What you receive

- Source code with full history in your repository
- Solution packages or app files ready to deploy
- Automated tests and instructions to run them
- A short technical design for each component
- Release notes for every deployment
- Handover notes: architecture, configuration, known limits

## How security is handled in custom code

Custom code runs with real permissions, so we design security with the feature, not after it.

- Dataverse plug-ins and custom APIs check the calling user's privileges. Code that must run with elevated rights does so on purpose, and the design says why.
- Business Central extensions use permission sets that grant only what each feature needs.
- Secrets such as API keys stay out of code and solution files. They belong in a managed secret store.
- Integration accounts get the smallest role that works, and we document who owns them.

## What affects the cost and timing of development work

We estimate after the requirement and the existing system are clear. These factors move the estimate most:

- The number of components and how many existing customizations they touch.
- Integrations with other systems, and how well those systems are documented.
- Data volumes, which decide whether logic must be asynchronous or batched.
- The depth of testing your industry or auditors require.
- Whether a working release process exists, or must be set up first.
- The quality of existing code that the new work has to call or replace.

Microsoft licenses are a separate cost, bought through Microsoft's channels; Business Central is sold only through Cloud Solution Provider (CSP) partners. Our [Microsoft Dynamics 365 implementation cost guide](https://msdynamicsguys.com/resources/dynamics-365-implementation-cost/) explains how to separate licenses, delivery work and support in a budget.

## When MS Dynamics Guys fits

MS Dynamics Guys fits companies that already run Microsoft Dynamics 365 Sales, Customer Service, Field Service or Business Central and need code that a future team can maintain: reviewed, tested and stored in their own repository.

### A good fit when

- A requirement goes beyond what configuration and flows can do safely.
- You want the code, tests and history in your own repository.
- Our developers need to work with your internal team or another partner.
- You need an integration endpoint or a custom API that other systems will depend on.

### Choose another route when

- A standard feature or a Microsoft Marketplace app meets the need at lower cost.
- You need a fixed price before anyone has looked at the existing system.
- You only need licenses. A Microsoft licensing partner is the right contact.

## Can MS Dynamics Guys take over custom code another partner built?

Yes, after a review. Taking over code without one hides risk in the first incident. The review needs:

- The source code, or at least the latest solution files or app packages, plus any build scripts.
- Access to a sandbox, and read access to production for comparing configuration.
- A list of integrations, scheduled jobs and the accounts they use.
- Recent incidents and any changes made directly in production.

For Business Central, check early whether you hold the AL source. Extensions hide their source by default unless the publisher allows download or includes source in symbols. If you do not own the source, ask the previous partner for it before the contract ends.

The review produces a written inventory: components, dependencies, unsupported customizations, missing tests and the fixes that come first. You can use it with us or with any other team.

## Questions buyers ask about Microsoft Dynamics 365 development

### Will you write code for every requirement?

No. MS Dynamics Guys checks standard features, Microsoft Marketplace apps and connectors first. We recommend code when these options cannot meet the requirement at an acceptable cost and maintenance level. The design records why code is needed and who will maintain it.

### Who owns the code you write?

The code is in your repository from the first commit, so you hold the complete history whoever maintains it next. Intellectual property terms are agreed in the contract before work starts.

### How do you test custom Microsoft Dynamics 365 code?

Business logic is written so that it can run in automated tests. Business Central extensions use AL test codeunits, which run in a container-based environment as Microsoft recommends for large test runs; online sandboxes allow only limited test runs. Dataverse plug-ins are structured so their rules run in unit tests without a live environment.

Integration and user tests then run in a test environment before anything reaches production.

### What happens to custom code during Microsoft Dynamics 365 updates?

Microsoft updates the cloud products on its own schedule. Business Central online gets two major updates a year, in April and October, plus monthly minor updates.

We test extensions against preview or sandbox environments before an update reaches production, and we fix any deprecated objects or APIs the update affects.

### Can your developers work alongside our team?

Yes. MS Dynamics Guys developers can work in your repository, follow your branch rules and join your code review process. If your lead will assign and accept their daily work, use [Microsoft Dynamics 365 staff augmentation](https://msdynamicsguys.com/services/dynamics-365-staff-augmentation/). If you want a defined change delivered as a project, agree its scope, acceptance criteria and handover before work starts.

### Can you fix performance problems in existing customizations?

MS Dynamics Guys first reviews where time is spent, such as synchronous plug-ins, frequent integration calls or reports reading too much data. The findings determine whether a code change, data clean-up or a different integration pattern is needed. We agree the proposed change and how to measure its effect before promising a fix.

## Related services and guides

- [Microsoft Dynamics 365 CRM](https://msdynamicsguys.com/solutions/dynamics-365-crm/): MS Dynamics Guys configures and extends Microsoft Dynamics 365 CRM apps on Dataverse, using plug-ins, custom APIs and PCF only where needed.
- [Business Central development](https://msdynamicsguys.com/solutions/business-central/development/): MS Dynamics Guys builds Business Central AL extensions, reports, APIs and integrations with automated tests, controlled dependencies and update testing.
- [Microsoft Dynamics 365 integration](https://msdynamicsguys.com/services/dynamics-365-integration/): MS Dynamics Guys connects Microsoft Dynamics 365 to ecommerce, ERP, CRM and data platforms, with record ownership, error handling and reconciliation.
- [Power Apps development](https://msdynamicsguys.com/power-platform/power-apps-development/): MS Dynamics Guys builds canvas and model-driven Power Apps with Dataverse, secure connections, license checks and managed-solution ALM.
- [Microsoft Dynamics 365 support](https://msdynamicsguys.com/services/dynamics-365-support/): MS Dynamics Guys supports Microsoft Dynamics 365 after go-live with code and integration fixes, release testing and an agreed enhancement backlog.
- [Hire experts](https://msdynamicsguys.com/hire/): Choose Microsoft Dynamics 365 developers and consultants from MS Dynamics Guys by product and role, with your team directing their work.
- [Microsoft Dynamics 365 implementation cost](https://msdynamicsguys.com/resources/dynamics-365-implementation-cost/): Plan Microsoft Dynamics 365 implementation costs: licenses, delivery, migration, integration, testing and support, with an estimate worksheet.
- [How we work](https://msdynamicsguys.com/how-we-work/): Discovery inputs, responsibilities, environments, testing, acceptance, source ownership and handover: how MS Dynamics Guys runs Microsoft Dynamics 365 projects.

## Tell us what Microsoft Dynamics 365 has to do

Send the requirement, app and version, and what you have already tried. Say whether you need a defined change delivered or a developer directed by your lead. Do not send passwords or live customer records. We reply with questions or a proposed next step.

[Discuss a development project](https://msdynamicsguys.com/contact/#intent=project&service=S01) · [Hire a Microsoft Dynamics 365 developer](https://msdynamicsguys.com/hire/)

## Product documentation referenced on this page

- [Plug-ins and supported customizations in Dataverse](https://learn.microsoft.com/en-us/power-apps/developer/data-platform/supported-customizations) (checked 2026-10-02)
- [Solution concepts for application lifecycle management](https://learn.microsoft.com/en-us/power-platform/alm/solution-concepts-alm) (checked 2026-10-02)
- [Programming in AL](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-programming-in-al) (checked 2026-10-02)
- [Calling .NET from AL (on-premises only)](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-get-started-call-dotnet-from-al) (checked 2026-10-02)
- [Business Central update rollout timeline](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/administration/update-rollout-timeline) (checked 2026-10-02)
- [Resource exposure policy setting (Business Central)](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-security-settings-and-ip-protection) (checked 2026-10-02)