diff --git a/.github/workflows/backend-build.yml b/.github/workflows/backend-build.yml
index 78d44815d7..aba02c3609 100644
--- a/.github/workflows/backend-build.yml
+++ b/.github/workflows/backend-build.yml
@@ -1,7 +1,7 @@
 name: Backend build, format check, and coverage
 
-# Reusable workflow called from build.yml. Runs the full backend build matrix
-# (JDK 21/25 × spring-security on/off), Spotless formatting check, JUnit, and
+# Reusable workflow called from build.yml. Runs the backend build matrix
+# (JDK 25 × spring-security on/off), Spotless formatting check, JUnit, and
 # posts Jacoco coverage to PRs.
 on:
   workflow_call:
diff --git a/AGENTS.md b/AGENTS.md
index fa0340c276..7a9ab7b304 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -431,7 +431,7 @@ The frontend is organized with a clear separation of concerns:
 
 ## Important Notes
 
-- **Java Version**: Minimum JDK 21, supports and recommends JDK 25
+- **Java Version**: Requires JDK 25 (raised from 21 to support JPDFium's FFM bindings, which target `org.gradle.jvm.version=25`).
 - **Lombok**: Used extensively - ensure IDE plugin is installed
 - **File Persistence**:
   - **Backend**: Designed to be stateless - files are processed in memory/temp locations only
diff --git a/DeveloperGuide.md b/DeveloperGuide.md
index fdfab20c5e..a9e7c1c106 100644
--- a/DeveloperGuide.md
+++ b/DeveloperGuide.md
@@ -11,7 +11,7 @@ This guide focuses on developing for Stirling 2.0, including both the React fron
 **Stirling 2.0** is built using:
 
 **Backend:**
-- Spring Boot (Java 21+, JDK 25 recommended)
+- Spring Boot (requires JDK 25)
 - PDFBox for core PDF operations
 - LibreOffice for document conversions
 - qpdf for PDF optimization
@@ -45,7 +45,7 @@ This guide focuses on developing for Stirling 2.0, including both the React fron
 - [Task](https://taskfile.dev/installation/) — unified command runner (recommended)
 - Docker
 - Git
-- Java JDK 21 or later (JDK 25 recommended)
+- Java JDK 25 (required — JPDFium FFM bindings target JVM 25)
 - Node.js 18+ and npm (required for frontend development)
 - Gradle 7.0 or later (Included within the repo)
 - [uv](https://docs.astral.sh/uv/) — Python package manager (required for engine development)
@@ -61,7 +61,7 @@ This guide focuses on developing for Stirling 2.0, including both the React fron
    cd Stirling-PDF
    ```
 
-2. Install Docker and JDK 21 (or JDK 25 recommended) if not already installed.
+2. Install Docker and JDK 25 if not already installed.
 
 3. Install a recommended Java IDE such as Eclipse, IntelliJ, or VSCode
    1. Only VSCode