diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4080c6f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,24 @@
+# Eclipse
+.classpath
+.project
+.settings/
+
+# Intellij
+.idea/
+*.iml
+*.iws
+
+# VSCode
+bin/
+
+# Mac
+.DS_Store
+
+# Smithy
+.smithy.lsp.log
+
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build/
diff --git a/README.md b/README.md
index 27287f5..688c703 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,11 @@
 # InAndOut-API-Modelling
-Module used to create clients (standard data types and classes) for our services and interfaces
+
+Complete API model for our system.
+
+References:
+
+- https://docs.google.com/document/d/1HnRcB2SaG4f4QodOaaYZT4r4GYhibqBzA8wdl2zpID0/edit?tab=t.h8qwaqvashle
+- https://openapi-converter.com/json-to-yaml
+- https://editor.swagger.io/
+- https://smithy.io/2.0/languages/java/client/generating-clients.html
+- https://smithy.io/2.0/guides/using-code-generation/generating-a-client.html
diff --git a/smithy-build.json b/smithy-build.json
new file mode 100644
index 0000000..e326f5a
--- /dev/null
+++ b/smithy-build.json
@@ -0,0 +1,42 @@
+{
+  "version": "1.0",
+  "outputDirectory": "build/",
+  "sources": ["smithy/model/"],
+  "maven": {
+    "dependencies": [
+      "software.amazon.smithy:smithy-aws-traits:1.68.0",
+      "software.amazon.smithy:smithy-openapi:1.68.0",
+      "software.amazon.smithy:smithy-linters:1.68.0",
+      "software.amazon.smithy.typescript:smithy-aws-typescript-codegen:0.45.0",
+      "software.amazon.smithy.java:client-codegen:0.0.3",
+      "software.amazon.smithy.java:client-core:0.0.3"
+    ]
+  },
+  "projections": {
+    "openapi-spec": {
+      "plugins": {
+        "openapi": {
+          "service": "com.shopping.inandout#InAndOut",
+          "protocol": "aws.protocols#restJson1",
+          "version": "3.1.0"
+        }
+      }
+    },
+    "java-client": {
+      "plugins": {
+        "java-client-codegen": {
+          "service": "com.shopping.inandout#InAndOut",
+          "namespace": "com.shopping.inandout"
+        }
+      }
+    },
+    "typescript-client": {
+      "plugins": {
+        "typescript-codegen": {
+          "package": "@inandout/client",
+          "packageVersion": "0.0.1"
+        }
+      }
+    }
+  }
+}
diff --git a/smithy/model/common.smithy b/smithy/model/common.smithy
new file mode 100644
index 0000000..90426d1
--- /dev/null
+++ b/smithy/model/common.smithy
@@ -0,0 +1,11 @@
+$version: "2"
+
+namespace com.shopping.inandout
+
+@pattern("^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$")
+@length(min: 36, max: 36)
+string UUID
+
+list UUIDList {
+    member: UUID
+}
diff --git a/smithy/model/errors.smithy b/smithy/model/errors.smithy
new file mode 100644
index 0000000..ebf0291
--- /dev/null
+++ b/smithy/model/errors.smithy
@@ -0,0 +1,38 @@
+$version: "2"
+
+namespace com.shopping.inandout
+
+@error("client")
+@httpError(400)
+structure InvalidInputError {
+    @required
+    message: String
+}
+
+@error("client")
+@httpError(404)
+structure ResourceNotFoundError {
+    @required
+    message: String
+}
+
+@error("client")
+@httpError(409)
+structure ResourceAlreadyExistsError {
+    @required
+    message: String
+}
+
+@error("client")
+@httpError(409)
+structure DeleteRestrictedError {
+    @required
+    message: String
+}
+
+@error("server")
+@httpError(500)
+structure InternalServerError {
+    @required
+    message: String
+}
diff --git a/smithy/model/main.smithy b/smithy/model/main.smithy
new file mode 100644
index 0000000..adae545
--- /dev/null
+++ b/smithy/model/main.smithy
@@ -0,0 +1,14 @@
+$version: "2"
+
+namespace com.shopping.inandout
+
+use com.shopping.inandout.tsp#FindTspSolution
+use aws.protocols#restJson1
+
+@restJson1
+service InAndOut {
+    version: "2026-04-01"
+    operations: [
+        FindTspSolution
+    ]
+}
diff --git a/smithy/model/tsp/tsp-apis.smithy b/smithy/model/tsp/tsp-apis.smithy
new file mode 100644
index 0000000..ee0eb1b
--- /dev/null
+++ b/smithy/model/tsp/tsp-apis.smithy
@@ -0,0 +1,19 @@
+$version: "2"
+
+namespace com.shopping.inandout.tsp
+
+use com.shopping.inandout#InternalServerError
+use com.shopping.inandout#InvalidInputError
+use com.shopping.inandout#ResourceNotFoundError
+
+@http(method: "POST", uri: "/tsp")
+@documentation("Travelling salesman problem solution creation/retrieval operation")
+operation FindTspSolution {
+    input: FindTspSolutionInput
+    output: FindTspSolutionOutput
+    errors: [
+        InvalidInputError
+        ResourceNotFoundError
+        InternalServerError
+    ]
+}
diff --git a/smithy/model/tsp/tsp-io.smithy b/smithy/model/tsp/tsp-io.smithy
new file mode 100644
index 0000000..24c4b15
--- /dev/null
+++ b/smithy/model/tsp/tsp-io.smithy
@@ -0,0 +1,15 @@
+$version: "2"
+
+namespace com.shopping.inandout.tsp
+
+use com.shopping.inandout#UUIDList
+
+structure FindTspSolutionInput {
+    @required
+    standIdList: UUIDList
+}
+
+structure FindTspSolutionOutput {
+    @required
+    solutionList: SolutionList
+}
diff --git a/smithy/model/tsp/tsp-types.smithy b/smithy/model/tsp/tsp-types.smithy
new file mode 100644
index 0000000..214f970
--- /dev/null
+++ b/smithy/model/tsp/tsp-types.smithy
@@ -0,0 +1,16 @@
+$version: "2"
+
+namespace com.shopping.inandout.tsp
+
+use com.shopping.inandout#UUIDList
+
+@documentation("Optimal market route")
+structure Solution {
+    @required
+    @documentation("Ordered location list of the selected articles")
+    nodeIdList: UUIDList
+}
+
+list SolutionList {
+    member: Solution
+}