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This page covers the operating systems, architectures, and languages supported by the locally installed on-premise version of the Symmetry Tax Engine (STE), along with sizing guidance. (The hosted API has no local requirements — you only need an HTTPS client.)

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Supported languages

The on-premise SDK ships with native interfaces for:
  • C / C++
  • Java
  • .NET
Java requires a Java Development Kit (JDK), version 11 or later. The Windows distributions also include a Delphi / Pascal interface unit (ste-interface-files/delphi/STE.pas). It is source only — you compile it into your own project — and it is not part of the Linux or macOS distributions. For .NET, the distribution includes interface assemblies for more than one target so you can match your existing runtime. Every one of them is named ste-net-core.dll; they differ only in which folder under ste-interface-files they sit in. Between .NET 8 and .NET Standard 2.0 you can reach .NET Framework 4.6.1 and later, .NET Core 2.0 and later, and every version of .NET from 5 onward — which is to say every .NET runtime Microsoft still supports. If you target .NET Framework, reference ste-interface-files/dotnet standard 2.0/ste-net-core.dll. You do not need to migrate to .NET 8 to stay current.
For new .NET integrations, target .NET 8. The .NET Standard assemblies are there for existing integrations.
There is no longer a .NET Framework assembly (ste-net.dll). It shipped only in the retired Visual Studio 2010 and 2013 Windows artifacts, whose final release was 2026.8.1. If your integration still references ste-net.dll, switch the reference to ste-interface-files/dotnet standard 2.0/ste-net-core.dll — see Migrating STE Windows legacy MSVCRT artifacts to UCRT..NET Framework 4.6.0 and earlier, and .NET Core 1.x, are no longer reachable. Those runtimes are all past Microsoft’s own end of support.
Each language has its own quickstart:

Java SDK

.NET SDK

C/C++ SDK

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Operating systems and architectures

The On-Premise STE runs on Windows, Linux, and macOS. Which architectures are available depends on the platform: There is no Windows ARM64 build. The engine’s shared library must be on your application’s library search path. A download unzips into a single flat directory — your STE directory — with the shared library, the tax database, and the ste-interface-files folder all at the top level.
Append your STE directory to the system Path environment variable (under Advanced System Settings > Environment Variables > System Variables), or copy ste.dll directly into your project’s build output. If you use the Java interface, copy jnidispatch.dll alongside it.Windows artifacts get the C standard library from the Universal C Runtime, which is built into Windows 10 and later. They also need VCRUNTIME140.dll, MSVCP140.dll, and on x64 VCRUNTIME140_1.dll, which come from the Visual C++ Redistributable — install the latest. Windows does not provide those three files, and the STE package does not include them.Your compiler version need not match the one used to build the engine. See Linking the native library.Both 64-bit and 32-bit builds are available. When targeting .NET Framework 4.5 or higher with the 64-bit engine, make sure Prefer 32-bit is unchecked in your project’s build settings.
Regardless of platform, your STE directory holds the engine library, the tax database (ste.db), ste.conf, versions.json, a log directory, and an ste-interface-files folder containing the C header, the Java JAR, the .NET assemblies, and the JSON/XML schemas.Each package also ships the JNA dispatch library next to the engine — jnidispatch.dll on Windows, libjnidispatch.so on Linux, libjnidispatch.jnilib on macOS. The Java interface needs it, so keep it alongside the engine library wherever you put that.Licensing is by key. Set the STE_LICENSE_KEY environment variable, or place your ste-license.dat file in your STE directory — the engine checks the environment variable first.

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Footprint and sizing

The On-Premise STE is deliberately lightweight. The engine is written in C and uses SQLite and Lua, so it runs tax calculations in milliseconds with a small on-disk footprint.

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Application footprint

The installed engine is compact. On Win64, for example:
  • Tax database (ste.db): about 31 MB
  • Engine library (ste.dll): about 4 MB
A full Win64 installation — the database, the engine, and every interface file — unpacks to just under 40 MB, from an 11 MB download. The tax database dominates, and it grows a little with each release as new tax years and jurisdictions are added. A macOS installation runs larger, around 50 MB, because the shared library is universal and carries code for both architectures.

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Sizing your environment

Symmetry does not publish fixed CPU, memory, or disk requirements for the On-Premise STE. Because the engine is so lightweight, hardware is rarely the constraint — appropriate sizing depends on your own workload (how many pay calculations you run in parallel and how you architect your application) far more than on the engine itself. Size your machine (or machines, in an n-tier architecture) for the amount of parallel processing your workload requires. If you’d like guidance for a specific deployment, contact Symmetry.

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Concurrency and scaling

The STE is built for high-volume, parallel payroll. In a multi-threaded environment, multiple engine instances can be checked out of a built-in pool, used, and returned for reuse by other threads without re-initializing. Initialization takes only milliseconds, but across thousands or tens of thousands of pay calculations that savings adds up.