diff --git a/.github/workflows/spectral-lint.yml b/.github/workflows/spectral-lint.yml
new file mode 100644
index 000000000..6a9a33fd0
--- /dev/null
+++ b/.github/workflows/spectral-lint.yml
@@ -0,0 +1,10 @@
+name: Spectral Lint
+on: [push, pull_request]
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+      - name: spectral-lint
+        run: ./validator/scripts/validate-all.sh
diff --git a/validator/scripts/validate-all.sh b/validator/scripts/validate-all.sh
new file mode 100755
index 000000000..728d53f9d
--- /dev/null
+++ b/validator/scripts/validate-all.sh
@@ -0,0 +1,74 @@
+#!/bin/bash
+#
+# Run this script from root folder in the repository
+#
+# To validate a single file: npx spectral lint <filename>.yaml --ruleset <ruleset>
+#
+
+# Ruleset
+ruleset="./validator/spectral.yaml"
+
+# Array of all YAML files
+files=(
+    "xero-identity.yaml"
+    "xero-projects.yaml"
+    "xero-app-store.yaml"
+    "xero-payroll-uk.yaml"
+    "xero_files.yaml"
+    "xero_accounting.yaml"
+    "xero-payroll-nz.yaml"
+    "xero_assets.yaml"
+    "xero_bankfeeds.yaml"
+    "xero-payroll-au.yaml"
+)
+
+total_files=${#files[@]}
+passed=0
+failed=0
+
+
+# Validate all Xero OpenAPI YAML files with the custom Spectral ruleset
+echo "🔍 Validating all Xero OpenAPI specifications..."
+echo "================================================"
+
+echo "Testing $total_files OpenAPI specification files..."
+echo ""
+
+for file in "${files[@]}"; do
+    if [ -f "$file" ]; then
+        echo "📄 Validating $file..."
+
+        # Run spectral and capture the exit code
+        if npx @stoplight/spectral-cli lint "$file" --ruleset "$ruleset" --quiet > /dev/null 2>&1; then
+            echo "✅ $file - PASSED"
+            ((passed++))
+        else
+            echo "❌ $file - FAILED"
+            echo "   Running detailed check:"
+            npx @stoplight/spectral-cli lint "$file" --ruleset "$ruleset" --format=stylish | head -10
+            echo ""
+            ((failed++))
+        fi
+    else
+        echo "⚠️  $file - FILE NOT FOUND"
+        ((failed++))
+    fi
+done
+
+echo ""
+echo "================================================"
+echo "📊 SUMMARY:"
+echo "   Total files: $total_files"
+echo "   Passed: $passed"
+echo "   Failed: $failed"
+
+if [ $failed -eq 0 ]; then
+    echo ""
+    echo "🎉 ALL FILES PASSED! The Spectral ruleset is working correctly."
+    echo "   This ruleset can be used as a baseline for validating future OpenAPI specs."
+    exit 0
+else
+    echo ""
+    echo "⚠️  Some files failed validation. Check the output above for details."
+    exit 1
+fi
diff --git a/validator/spectral.yaml b/validator/spectral.yaml
new file mode 100644
index 000000000..13eb80f27
--- /dev/null
+++ b/validator/spectral.yaml
@@ -0,0 +1,32 @@
+extends: ["spectral:oas", "./xero-spectral.yaml"]
+
+rules:
+  # Override default rules to be more lenient for existing Xero API specs
+
+  # Re-enabled: operation-description (produces warnings only - acceptable for documentation improvement)
+  # operation-description: off
+
+  # Disabled: info-description (xero_accounting.yaml missing description)
+  info-description: off
+
+  # Disabled: operation-tag-defined (many APIs use undeclared tags)
+  operation-tag-defined: off
+
+  # Disabled: no-$ref-siblings (xero_accounting.yaml uses this pattern with type field)
+  no-$ref-siblings: off
+
+  # Disabled: example validation rules (legacy string examples would cause many errors)
+  oas3-valid-media-example: off
+  oas3-valid-schema-example: off
+
+  # Re-enabled: oas3-unused-component (produces warnings only - helps identify unused schemas)
+  # oas3-unused-component: off
+
+  # Re-enabled: oas3-server-trailing-slash (produces warnings only - helps clean up URLs)
+  # oas3-server-trailing-slash: off
+
+  # Disabled: path-params (FileId/FolderId path conflicts in xero_files.yaml)
+  path-params: off
+
+  # Re-enabled: oas3-operation-security-defined (produces warnings only - helps identify security gaps)
+  # oas3-operation-security-defined: off
diff --git a/validator/xero-spectral.yaml b/validator/xero-spectral.yaml
new file mode 100644
index 000000000..9cfb37079
--- /dev/null
+++ b/validator/xero-spectral.yaml
@@ -0,0 +1,120 @@
+rules:
+  # Custom rules specific to Xero APIs
+  xero-info-required-fields:
+    description: "Ensure required info fields are present"
+    given: "$.info"
+    severity: error
+    then:
+      - field: "title"
+        function: truthy
+      - field: "version"
+        function: truthy
+      - field: "termsOfService"
+        function: truthy
+      - field: "contact"
+        function: truthy
+
+  xero-contact-required-fields:
+    description: "Ensure contact has required fields"
+    given: "$.info.contact"
+    severity: error
+    then:
+      - field: "name"
+        function: truthy
+      - field: "email"
+        function: truthy
+      - field: "url"
+        function: truthy
+
+  xero-servers-required:
+    description: "Ensure servers are defined"
+    given: "$"
+    severity: error
+    then:
+      field: "servers"
+      function: truthy
+
+  xero-server-description:
+    description: "Each server should have a description"
+    given: "$.servers[*]"
+    severity: warn
+    then:
+      field: "description"
+      function: truthy
+
+  xero-operation-summary:
+    description: "Operations should have summaries"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace]"
+    severity: warn
+    then:
+      field: "summary"
+      function: truthy
+
+  xero-operation-id:
+    description: "Operations must have operationId"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace]"
+    severity: error
+    then:
+      field: "operationId"
+      function: truthy
+
+  xero-operation-tags:
+    description: "Operations should have tags"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace]"
+    severity: warn
+    then:
+      field: "tags"
+      function: truthy
+
+  xero-operation-security:
+    description: "Operations should have security defined"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace]"
+    severity: info
+    then:
+      field: "security"
+      function: truthy
+
+  xero-response-200-description:
+    description: "200 responses should have descriptions"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace].responses.200"
+    severity: warn
+    then:
+      field: "description"
+      function: truthy
+
+  xero-schema-properties-description:
+    description: "Schema properties should have descriptions for better documentation"
+    given: "$.components.schemas[*].properties[*]"
+    severity: info
+    then:
+      field: "description"
+      function: truthy
+
+  xero-openapi-version:
+    description: "Should use OpenAPI 3.0.0 or higher"
+    given: "$.openapi"
+    severity: error
+    then:
+      function: pattern
+      functionOptions:
+        match: "^3\\.[0-9]+\\.[0-9]+$"
+
+  xero-path-parameters:
+    description: "Path parameters should be properly defined"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace].parameters[?(@.in === 'path')]"
+    severity: error
+    then:
+      - field: "name"
+        function: truthy
+      - field: "required"
+        function: truthy
+      - field: "schema"
+        function: truthy
+
+  xero-consistent-error-responses:
+    description: "Should have consistent error response structure"
+    given: "$.paths[*][get,post,put,patch,delete,head,options,trace].responses[?(@property >= '400')]"
+    severity: info
+    then:
+      field: "description"
+      function: truthy