Flight simulator SDK explained: MSFS 2024 and 2020 downloads and documentation, X-Plane tools, add-on uses, compatibility and common fixes.
A flight simulator SDK (software development kit) is the official set of documentation, tools, samples and programming interfaces used to create add-ons or connect external software. Depending on the simulator, it can support aircraft, airports, scenery, instruments, effects and missions, plus utilities that read or exchange navigation, weather, traffic and aircraft-state data.
The scope here is flight simulators generally, including Microsoft Flight Simulator, X-Plane and Prepar3D. There is no universal flight simulator SDK: each toolkit targets a particular simulator family, and often a particular generation or build.
What does a flight simulator SDK include?
A flight simulator SDK normally combines technical documentation with the tools and rules needed to turn editable source files into content the simulator can load.
- Documentation describing project structures, configuration properties, simulator variables, events, APIs and supported workflows.
- Editors and exporters for object placement, model conversion, animation data and other simulator-specific content.
- Compilers and build tools that convert source assets into runtime packages.
- Sample projects demonstrating valid aircraft, airport, gauge, plugin or application structures.
- Programming interfaces through which software can read simulator data, send supported commands or communicate with hardware.
- Logging and validation tools for identifying missing assets, invalid definitions, duplicate identifiers and build failures.
The SDK is rarely the whole workshop. A 3D modeller, image editor, audio editor, geographic-data tool and programming environment may all be separate. Our overview of the supporting modelling, coding, audio and packaging tools explains what normally sits alongside the official toolkit.
What can you make with a flight simulator SDK?
An SDK can support anything from one airport object to a complex aircraft or external telemetry application, but only the target simulator's documentation defines what is actually available.
| Project type | What the SDK provides | Typical additional work |
|---|---|---|
| Aircraft | Model definitions, flight dynamics, cockpit interactions, systems, sounds and package configuration | 3D modelling, texturing, research, configuration and systems programming |
| Airports and scenery | Object placement, airport data, buildings, materials, ground features and terrain-related inputs | Asset creation, geographical data preparation and performance optimisation |
| Instruments and avionics | Displays, gauges, simulator variables, controls and cockpit logic | Interface design, scripting or compiled code |
| Activities and effects | Triggers, missions, challenges, visual effects and other simulator-specific content | Logic, configuration and repeated in-simulator testing |
| External applications | Supported data access for moving maps, flight trackers, dispatch tools, telemetry and hardware bridges | Application programming and careful handling of the simulator's API |
Access is not automatically read/write. A published variable may be readable but not writable, and the simulator may retain authority over weather, traffic, failures or aircraft systems. Trying to force an undocumented or private value is a common cause of add-ons breaking after simulator updates.
An SDK also does not convert an add-on between simulators. Models, materials, flight dynamics, package manifests and code usually require separate export, configuration and testing for every supported platform.
How do SDKs, APIs and Developer Mode differ?
The SDK is the overall development kit, an API is a defined interface for communicating with the simulator, and Developer Mode is an in-simulator workspace provided by some platforms.
One project may use all three. An airport can be arranged in Developer Mode, built with SDK tools and accompanied by an application that exchanges data through an API. In Microsoft Flight Simulator and Prepar3D, SimConnect is an important API for external software; it is not the entire SDK.
End users usually do not need the SDK to install a finished add-on. They need the correctly packaged release and any redistributable runtime or dependency specified by its developer.
Which flight simulator SDK should you use?
Use the SDK and documentation for the exact simulator generation you intend to support, then confirm any build-specific requirements before starting the project.
| Target simulator | Development route | Main compatibility warning |
|---|---|---|
| Microsoft Flight Simulator 2024 | MSFS 2024 Developer Mode, its matching SDK tools and MSFS 2024 SDK documentation | Do not assume an MSFS 2020 project, sample or compiled package is a valid 2024 project without migration and testing |
| Microsoft Flight Simulator 2020 | MSFS 2020 Developer Mode, the 2020 SDK and its generation-specific documentation | A tutorial or tool labelled only for 2024 may use definitions unavailable in 2020 |
| X-Plane | The Plugin SDK for compiled plugins; Plane Maker, Airfoil Maker and scenery tools for their respective content types | The Plugin SDK is not a universal aircraft and scenery builder, and plugin binaries must support the user's operating system and architecture |
| Prepar3D | The SDK matching the intended Prepar3D generation and, where required, its simulator build | Mismatched exporters, libraries or SimConnect components can fail before the add-on itself is tested |
| FSX and Flight Simulator 2004 | The release-specific legacy SDK components and compatible authoring software | Old exporters and utilities may depend on obsolete host applications, runtimes or installation assumptions |
For a concrete modern example, our practical MSFS SDK setup walkthrough covers Developer Mode, packages, building, SimConnect and first-project testing. Prepar3D developers should instead follow the Prepar3D v5 SDK installation and version-matching process.
Where is the MSFS SDK download, and which documentation should you use?
The official MSFS SDK download is provided through the simulator's development environment on Windows PC, while the documentation must be selected for either MSFS 2020 or MSFS 2024.
- Launch the target simulator on PC. Open the same Microsoft Flight Simulator generation for which you plan to build the add-on.
- Enable Developer Mode. Microsoft may move its surrounding settings between updates, but the simulator's development options provide access to DevMode.
- Use the official SDK installer route exposed by DevMode. Avoid repackaged installers because their version and contents may not match the simulator.
- Open the matching SDK documentation. Check that examples and reference pages explicitly target MSFS 2020 or MSFS 2024 before copying their configuration.
- Build an unchanged sample first. This separates installation faults from mistakes in custom models, code or package definitions.
MSFS 2024 is available on PC, Xbox Series X|S and PlayStation 5, but SDK authoring is a PC workflow. MSFS 2020 is available on PC and Xbox, not PlayStation. Consoles do not offer the desktop SDK environment or unrestricted loading of locally built development packages; console releases must use the platform's approved publishing route.
Are the MSFS 2024 and MSFS 2020 SDKs interchangeable?
MSFS 2024 and MSFS 2020 have distinct SDK documentation and build targets, even where concepts and project layouts look familiar.
“MSFS 24 SDK” is simply shorthand for the MSFS 2024 SDK, not an update that should be installed over a 2020 project without checking migration guidance. Preserve the working 2020 source, migrate a copy, rebuild it with the 2024 toolchain and resolve every schema, asset and validation warning before release.
Some assets and external SimConnect applications may require fewer changes than an aircraft or airport package, but visual success at one location or in one aircraft is not proof of compatibility. Test loading, interactions, dependencies, performance and clean installation in the actual target simulator.
How is the X-Plane SDK different?
The X-Plane SDK usually means the Plugin SDK: headers, libraries, examples and documentation for C or C++ plugins that interact with X-Plane through published functions, datarefs and commands.
It is not the normal tool for every type of X-Plane add-on. Aircraft geometry and flight characteristics are handled through Plane Maker and related asset tools, while scenery creation uses the appropriate scenery editor and documented file formats. A plugin is the right choice when the project needs compiled logic, custom systems, hardware communication or data access that ordinary aircraft and scenery definitions cannot provide.
- Use documented datarefs and commands. Some datarefs are read-only, and private internal values can change without compatibility guarantees.
- Build for each supported platform. A binary compiled for one operating system or processor architecture will not automatically load on another.
- Follow the required plugin folder structure. A correctly compiled binary in the wrong location is still invisible to the simulator.
- Read
Log.txt. It normally reveals an unsupported binary, missing dependency, failed plugin load or runtime error more clearly than the on-screen symptoms.
Obtain the Plugin SDK from its official developer distribution and use the API reference matching the features you call. An older API level may remain suitable for a simple plugin, while newer functions require the corresponding SDK definitions and a compatible X-Plane release.
What is a safe first SDK project?
The safest first project is a minimal change that builds quickly and produces an obvious result in the simulator.
- Choose one simulator and one add-on type. Cross-simulator support is a later porting task, not a sensible first milestone.
- Install the matching SDK and prerequisites. Confirm that exporters, compilers and host applications support each other.
- Build an official sample unchanged. If that fails, repair the toolchain before adding custom work.
- Change one thing. Place one scenery object, replace one texture or display one documented simulator value.
- Inspect the complete build log. Resolve missing files, duplicate identifiers and invalid paths rather than treating warnings as background noise.
- Test the compiled output. Load the package or plugin as a user would, without relying on files left in the source directory.
- Test a clean installation. Remove duplicate development copies and verify that every distributable dependency is included or documented.
Scenery placement or a simple data-reading utility is generally easier to diagnose than a complete aircraft. For the broader sequence after this first build, see our add-on workflow from project selection through packaging and release testing.
Why does an SDK project build but not appear in the simulator?
A successful compiler message does not prove that the simulator found, accepted or loaded the resulting package.
| Symptom | Likely cause | Practical fix |
|---|---|---|
| Package does not appear | Wrong output location, invalid package metadata, incompatible target or missing dependency | Check the simulator log, verify the target generation and test the official sample in the same location |
| Old content appears after rebuilding | A stale package or duplicate identifier is loading first | Remove duplicate test copies, clear only the documented development cache where applicable and restart the simulator |
| Changes vanish on the next build | Generated output was edited instead of the source project | Keep editable source and compiled output separate, then change only the source |
| Exporter or editor will not start | SDK, simulator, host application or prerequisite mismatch | Confirm supported versions before reinstalling the entire simulator |
| Variable can be read but not changed | The API exposes it as read-only or the simulator owns that state | Use a documented writable event, command or variable rather than forcing internal data |
| X-Plane plugin is ignored | Wrong binary platform, folder structure or missing runtime dependency | Inspect Log.txt and verify the binary for that operating system and architecture |
| Works only on the developer's machine | Undeclared local files, absolute paths or unshipped dependencies | Install the release into a clean test setup and remove access to the source directory |
Across add-on libraries, source/output confusion and duplicate packages are two mistakes we see repeatedly. Change one variable at a time; replacing the SDK, project structure and custom assets together makes the actual fault much harder to identify.
Do you need programming knowledge to use an SDK?
You do not need advanced programming for every SDK project, but every project requires disciplined file handling, version control and testing.
- Choose liveries or simple scenery when your strengths are texture work, modelling and visual placement.
- Choose aircraft configuration when you are comfortable editing structured files and repeatedly testing flight behaviour.
- Choose instruments, plugins or external utilities when you want to work with code, events, data types and simulator APIs.
Complex avionics and aircraft systems are software projects even when much of their presentation is graphical. Start with one documented value or interaction before attempting a complete display or flight-management system.
Can SDK add-ons be shared or sold?
SDK add-ons can often be distributed as freeware or commercial products, subject to the simulator's SDK licence, third-party asset licences and any applicable publishing rules.
Building a package does not grant permission to redistribute default aircraft models, textures, sounds, documentation or SDK tools. Keep records for every original and third-party asset, check whether required runtime components may be redistributed, and test that the release contains compiled deliverables rather than private source material or simulator-owned files.