diff --git a/lib/dsn-pcb/circuit-json-to-dsn-json/stringify-dsn-session.ts b/lib/dsn-pcb/circuit-json-to-dsn-json/stringify-dsn-session.ts
new file mode 100644
index 0000000..ac8c7ac
--- /dev/null
+++ b/lib/dsn-pcb/circuit-json-to-dsn-json/stringify-dsn-session.ts
@@ -0,0 +1,77 @@
+import type { DsnSession } from "../types"
+
+export const stringifyDsnSession = (session: DsnSession): string => {
+  const indent = "  "
+  let result = ""
+
+  // Start with session
+  result += `(session ${session.filename}\n`
+
+  // Base design
+  result += `${indent}(base_design ${session.filename})\n`
+
+  // Placement section
+  result += `${indent}(placement\n`
+  result += `${indent}${indent}(resolution ${session.placement.resolution.unit} ${session.placement.resolution.value})\n`
+  session.placement.components.forEach((component) => {
+    result += `${indent}${indent}(component ${component.name}\n`
+    result += `${indent}${indent}${indent}(place ${component.place.refdes} ${component.place.x} ${component.place.y} ${component.place.side} ${component.place.rotation})\n`
+    result += `${indent}${indent})\n`
+  })
+  result += `${indent})\n`
+
+  // Was_is section (if needed)
+  result += `${indent}(was_is\n${indent})\n`
+
+  // Routes section
+  result += `${indent}(routes \n`
+  result += `${indent}${indent}(resolution ${session.routes.resolution.unit} ${session.routes.resolution.value})\n`
+
+  // Parser subsection
+  result += `${indent}${indent}(parser\n`
+  result += `${indent}${indent}${indent}(host_cad ${JSON.stringify(session.routes.parser.host_cad)})\n`
+  result += `${indent}${indent}${indent}(host_version ${JSON.stringify(session.routes.parser.host_version)})\n`
+  result += `${indent}${indent})\n`
+
+  // Library_out subsection
+  if (session.routes.library_out) {
+    result += `${indent}${indent}(library_out \n`
+    session.routes.library_out.padstacks.forEach((padstack) => {
+      result += `${indent}${indent}${indent}(padstack ${JSON.stringify(padstack.name)}\n`
+      padstack.shapes.forEach((shape) => {
+        if (shape.shapeType === "circle") {
+          result += `${indent}${indent}${indent}${indent}(shape\n`
+          result += `${indent}${indent}${indent}${indent}${indent}(circle ${shape.layer} ${shape.diameter} 0 0)\n`
+          result += `${indent}${indent}${indent}${indent})\n`
+        }
+      })
+      result += `${indent}${indent}${indent}${indent}(attach ${padstack.attach})\n`
+      result += `${indent}${indent}${indent})\n`
+    })
+    result += `${indent}${indent})\n`
+  }
+
+  // Network_out subsection
+  result += `${indent}${indent}(network_out \n`
+  session.routes.network_out.nets.forEach((net) => {
+    result += `${indent}${indent}${indent}(net ${JSON.stringify(net.name)}\n`
+    net.wires.forEach((wire) => {
+      if (wire.path) {
+        result += `${indent}${indent}${indent}${indent}(wire\n`
+        result += `${indent}${indent}${indent}${indent}${indent}(path ${wire.path.layer} ${wire.path.width}\n`
+        result += `${indent}${indent}${indent}${indent}${indent}${indent}${wire.path.coordinates.join(" ")}\n`
+        result += `${indent}${indent}${indent}${indent}${indent})\n`
+        result += `${indent}${indent}${indent}${indent})\n`
+      }
+    })
+    result += `${indent}${indent}${indent})\n`
+  })
+  result += `${indent}${indent})\n`
+
+  result += `${indent})\n`
+
+  // Close session
+  result += `)\n`
+
+  return result
+}
diff --git a/lib/index.ts b/lib/index.ts
index 873ca1e..20a1504 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -1,6 +1,7 @@
 export * from "./dsn-pcb/circuit-json-to-dsn-json/convert-circuit-json-to-dsn-json.ts"
 export * from "./dsn-pcb/circuit-json-to-dsn-json/convert-circuit-json-to-dsn-string.ts"
 export * from "./dsn-pcb/circuit-json-to-dsn-json/stringify-dsn-json.ts"
+export * from "./dsn-pcb/circuit-json-to-dsn-json/stringify-dsn-session.ts"
 export * from "./dsn-pcb/dsn-json-to-circuit-json/convert-dsn-json-to-circuit-json.ts"
 export * from "./dsn-pcb/dsn-json-to-circuit-json/parse-dsn-to-circuit-json.ts"
 export * from "./dsn-pcb/dsn-json-to-circuit-json/parse-dsn-to-dsn-json.ts"
diff --git a/tests/dsn-pcb/stringify-dsn-session.test.ts b/tests/dsn-pcb/stringify-dsn-session.test.ts
new file mode 100644
index 0000000..28220e7
--- /dev/null
+++ b/tests/dsn-pcb/stringify-dsn-session.test.ts
@@ -0,0 +1,27 @@
+import { expect, test } from "bun:test"
+import { parseDsnToDsnJson, stringifyDsnSession, type DsnSession } from "lib"
+// @ts-ignore
+import sessionFile from "../assets/freerouting-sessions/session1.ses" with {
+  type: "text",
+}
+
+test("stringify session file", () => {
+  const sessionJson = parseDsnToDsnJson(sessionFile) as DsnSession
+  const stringified = stringifyDsnSession(sessionJson)
+  const reparsed = parseDsnToDsnJson(stringified) as DsnSession
+
+  // Test that we can parse the generated string back to the same structure
+  expect(reparsed.filename).toBe(sessionJson.filename)
+  expect(reparsed.placement.components).toHaveLength(
+    sessionJson.placement.components.length,
+  )
+  expect(reparsed.routes.network_out.nets).toHaveLength(
+    sessionJson.routes.network_out.nets.length,
+  )
+
+  // Test specific values
+  const originalNet = sessionJson.routes.network_out.nets[0]
+  const reparsedNet = reparsed.routes.network_out.nets[0]
+  expect(reparsedNet.name).toBe(originalNet.name)
+  expect(reparsedNet.wires).toHaveLength(originalNet.wires.length)
+})