metab0t · metab0t · Feb 10, 2026 · Feb 7, 2026 · Feb 7, 2026 · Feb 7, 2026
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -264,6 +264,25 @@ if(DEFINED ENV{XPRESSDIR})
     target_include_directories(xpress_model_ext PRIVATE $ENV{XPRESSDIR}/include)
 endif()
 
+# KNITRO
+add_library(knitro_model STATIC)
+target_sources(knitro_model PRIVATE
+    include/pyoptinterface/knitro_model.hpp
+    lib/knitro_model.cpp
+)
+target_link_libraries(knitro_model PUBLIC core cppad_interface)
+
+nanobind_add_module(
+    knitro_model_ext
+
+    STABLE_ABI NB_STATIC NB_DOMAIN pyoptinterface
+
+    lib/knitro_model_ext.cpp
+    lib/knitro_model_ext_constants.cpp
+)
+target_link_libraries(knitro_model_ext PUBLIC knitro_model)
+install(TARGETS knitro_model_ext LIBRARY DESTINATION ${POI_INSTALL_DIR})
+
 # stub
 nanobind_add_stub(
   core_ext_stub
@@ -342,6 +361,13 @@ nanobind_add_stub(
   OUTPUT ${POI_INSTALL_DIR}/xpress_model_ext.pyi
 )
 
+nanobind_add_stub(
+  knitro_model_ext_stub
+  INSTALL_TIME
+  MODULE pyoptinterface._src.knitro_model_ext
+  OUTPUT ${POI_INSTALL_DIR}/knitro_model_ext.pyi
+)
+
 set(ENABLE_TEST_MAIN OFF BOOL "Enable test c++ function with a main.cpp")
 if(ENABLE_TEST_MAIN)
     add_executable(test_main lib/main.cpp)

diff --git a/docs/source/api/pyoptinterface.knitro.rst b/docs/source/api/pyoptinterface.knitro.rst
@@ -0,0 +1,8 @@
+pyoptinterface.knitro package
+====================================
+
+.. automodule:: pyoptinterface.knitro
+   :members:
+   :inherited-members:
+   :undoc-members:
+   :show-inheritance:
diff --git a/docs/source/attribute/knitro.md b/docs/source/attribute/knitro.md
@@ -0,0 +1,122 @@
+### Supported [model attribute](#pyoptinterface.ModelAttribute)
+
+:::{list-table}
+:header-rows: 1
+
+*   - Attribute
+    - Get
+    - Set
+*   - Name
+    - ❌
+    - ❌
+*   - ObjectiveSense
+    - ✅
+    - ✅
+*   - DualStatus
+    - ❌
+    - ❌
+*   - PrimalStatus
+    - ✅
+    - ❌
+*   - RawStatusString
+    - ✅
+    - ❌
+*   - TerminationStatus
+    - ✅
+    - ❌
+*   - BarrierIterations
+    - ✅
+    - ❌
+*   - DualObjectiveValue
+    - ❌
+    - ❌
+*   - NodeCount
+    - ✅
+    - ❌
+*   - NumberOfThreads
+    - ✅
+    - ✅
+*   - ObjectiveBound
+    - ✅
+    - ❌
+*   - ObjectiveValue
+    - ✅
+    - ❌
+*   - RelativeGap
+    - ✅
+    - ❌
+*   - Silent
+    - ❌
+    - ✅
+*   - SimplexIterations
+    - ❌
+    - ❌
+*   - SolverName
+    - ✅
+    - ❌
+*   - SolverVersion
+    - ✅
+    - ❌
+*   - SolveTimeSec
+    - ✅
+    - ❌
+*   - TimeLimitSec
+    - ✅
+    - ✅
+:::
+
+### Supported [variable attribute](#pyoptinterface.VariableAttribute)
+
+:::{list-table}
+:header-rows: 1
+
+*   - Attribute
+    - Get
+    - Set
+*   - Value
+    - ✅
+    - ❌
+*   - LowerBound
+    - ✅
+    - ✅
+*   - UpperBound
+    - ✅
+    - ✅
+*   - Domain
+    - ❌
+    - ✅
+*   - PrimalStart
+    - ❌
+    - ✅
+*   - Name
+    - ✅
+    - ✅
+*   - IISLowerBound
+    - ❌
+    - ❌
+*   - IISUpperBound
+    - ❌
+    - ❌
+*   - ReducedCost
+    - ✅
+    - ❌
+:::
+
+### Supported [constraint attribute](#pyoptinterface.ConstraintAttribute)
+
+:::{list-table}
+:header-rows: 1
+
+*   - Attribute
+    - Get
+    - Set
+*   - Name
+    - ✅
+    - ✅
+*   - Primal
+    - ✅
+    - ❌
+*   - Dual
+    - ✅
+    - ❌
+:::
diff --git a/docs/source/getting_started.md b/docs/source/getting_started.md
@@ -82,7 +82,7 @@ The typical paths where the dynamic library of optimizers are located are as fol
     - `/opt/gurobi1100/macos_universal2/lib`
     - `/opt/gurobi1100/macos_universal2/lib`
 *   - Xpress
-    - `C:\xpressmp\bin` 
+    - `C:\xpressmp\bin`
     - `/opt/xpressmp/lib`
     - `/Applications/FICO Xpress/xpressmp/lib`
     - `/Applications/FICO Xpress/xpressmp/lib`
@@ -101,7 +101,11 @@ The typical paths where the dynamic library of optimizers are located are as fol
     - `/opt/highs/lib`
     - `/opt/highs/lib`
     - `/opt/highs/lib`
-
+*   - KNITRO
+    - `C:\Program Files\Artelys\KNITRO 15.1\lib`
+    - `/opt/knitro/15.1/lib`
+    - `/opt/knitro/15.1/lib`
+    - `/opt/knitro/15.1/lib`
 :::
 
 ### Gurobi
@@ -158,6 +162,15 @@ For Ipopt, the automatic detection looks for the following things in order:
 
 We recommend using the official binary from [GitHub](https://github.com/coin-or/Ipopt/releases) if you work on Windows, since compiling Ipopt on Windows from source is not an easy task.
 
+### KNITRO
+
+The currently supported version is **15.1.x**. Other versions may work but are not tested.
+
+For KNITRO, the automatic detection looks for the following things in order:
+1. The environment variable `KNITRODIR` set by the installer of KNITRO
+2. `knitro.dll`/`libknitro.so`/`libknitro.dylib` in the system loadable path
+3. The installation of `knitro` PyPI package.
+
 ## Manually specifying the path of the dynamic library of optimizer
 
 If the automatic detection fails or you want to use the optimizer in a customized location, you can manually specify the path of the dynamic library of the optimizer.
@@ -211,7 +224,7 @@ The typical paths where the dynamic library of optimizers are located are as fol
     - `/opt/copt72/lib/libcopt.dylib`
     - `/opt/copt72/lib/libcopt.dylib`
 *   - Xpress
-    - `C:\xpressmp\bin\xprs.dll` 
+    - `C:\xpressmp\bin\xprs.dll`
     - `/opt/xpressmp/lib/libxprs.so`
     - `/Applications/FICO Xpress/xpressmp/lib/libxprs.dylib`
     - `/Applications/FICO Xpress/xpressmp/lib/libxprs.dylib`
@@ -225,7 +238,11 @@ The typical paths where the dynamic library of optimizers are located are as fol
     - `/opt/highs/lib/libhighs.so`
     - `/opt/highs/lib/libhighs.dylib`
     - `/opt/highs/lib/libhighs.dylib`
-
+*   - KNITRO
+    - `C:\Program Files\Artelys\KNITRO 15.1\lib\knitro.dll`
+    - `/opt/knitro/15.1/lib/libknitro.so`
+    - `/opt/knitro/15.1/lib/libknitro.dylib`
+    - `/opt/knitro/15.1/lib/libknitro.dylib`
 :::
 
 ## Let's build a simple model and solve it

diff --git a/docs/source/knitro.md b/docs/source/knitro.md
@@ -0,0 +1,118 @@
+# KNITRO
+
+## Initial setup
+
+```python
+from pyoptinterface import knitro
+
+model = knitro.Model()
+```
+
+You need to follow the instructions in [Getting Started](getting_started.md#knitro) to set up the optimizer correctly.
+
+## The capability of `knitro.Model`
+
+### Supported constraints
+
+:::{list-table}
+:header-rows: 1
+*   - Constraint
+    - Supported
+*   - <project:#model.add_linear_constraint>
+    - ✅
+*   - <project:#model.add_quadratic_constraint>
+    - ✅
+*   - <project:#model.add_second_order_cone_constraint>
+    - ✅
+*   - <project:#model.add_exp_cone_constraint>
+    - ❌
+*   - <project:#model.add_sos_constraint>
+    - ❌
+*   - <project:#model.add_nl_constraint>
+    - ✅
+:::
+
+```{include} attribute/knitro.md
+```
+
+## Solver-specific operations
+
+### Parameters
+
+For [solver-specific parameters](https://www.artelys.com/app/docs/knitro/2_userGuide/knitroOptions.html), we provide `get_raw_parameter` and `set_raw_parameter` methods to get and set the parameters.
+
+```python
+model = knitro.Model()
+
+# Set the value of a parameter by name
+model.set_raw_parameter("algorithm", 1)
+model.set_raw_parameter("feastol", 1e-8)
+model.set_raw_parameter("opttol", 1e-8)
+
+# Set the value of a parameter by ID (using knitro.KN constants)
+model.set_raw_parameter(knitro.KN.PARAM_MAXIT, 1000)
+```
+
+We also provide `knitro.KN` to contain common constants from the KNITRO C API.
+
+```python
+# Using constants for parameter IDs
+model.set_raw_parameter(knitro.KN.PARAM_FEASTOL, 1e-6)
+
+# Algorithm selection
+model.set_raw_parameter(knitro.KN.PARAM_NLP_ALGORITHM, knitro.KN.NLP_ALG_BAR_DIRECT)
+
+# Output level
+model.set_raw_parameter(knitro.KN.PARAM_OUTLEV, knitro.KN.OUTLEV_ITER)
+
+# MIP parameters
+model.set_raw_parameter(knitro.KN.PARAM_MIP_METHOD, knitro.KN.MIP_METHOD_BB)
+model.set_raw_parameter(knitro.KN.PARAM_MIP_OPTGAPREL, 1e-4)
+```
+
+### Variable and Constraint Properties
+
+Common variable and constraint properties are provided through PyOptInterface dedicated methods:
+
+**Variable methods:**
+- **Bounds**: `set_variable_lb`, `get_variable_lb`, `set_variable_ub`, `get_variable_ub`
+- **Type and name**: `set_variable_name`, `get_variable_name`, `set_variable_domain`
+- **Starting point**: `set_variable_start`
+- **Solution values**: `get_value`, `get_variable_rc`
+
+**Constraint methods:**
+- **Name**: `set_constraint_name`, `get_constraint_name`
+- **Solution values**: `get_constraint_primal`, `get_constraint_dual`
+
+**Usage examples:**
+
+Variable properties:
+```python
+# Bounds
+model.set_variable_lb(variable, 0.0)
+lb = model.get_variable_lb(variable)
+model.set_variable_ub(variable, 10.0)
+ub = model.get_variable_ub(variable)
+
+# Type and name
+model.set_variable_name(variable, "x")
+name = model.get_variable_name(variable)
+
+# Starting point
+model.set_variable_start(variable, 1.0)
+
+# Solution values
+value = model.get_value(variable)
+rc = model.get_variable_rc(variable)
+```
+
+Constraint properties:
+```python
+# Name
+model.set_constraint_name(constraint, "c1")
+name = model.get_constraint_name(constraint)
+
+# Solution values
+primal = model.get_constraint_primal(constraint)
+dual = model.get_constraint_dual(constraint)
+```
diff --git a/include/pyoptinterface/core.hpp b/include/pyoptinterface/core.hpp
@@ -274,7 +274,8 @@ enum class ConstraintType
 	COPT_ExpCone,
 	COPT_NL,
 	IPOPT_NL,
-	Xpress_Nlp
+	Xpress_Nlp,
+	KNITRO_NL,
 };
 
 enum class SOSType