diff --git a/src/backend/src/api/validators/metrics.validator.ts b/src/backend/src/api/validators/metrics.validator.ts
new file mode 100644
index 0000000..5657011
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+++ b/src/backend/src/api/validators/metrics.validator.ts
@@ -0,0 +1,257 @@
+/**
+ * @fileoverview Implements comprehensive validation schemas and middleware for metrics-related API requests
+ * Ensures data integrity and security through robust validation rules with caching and performance optimization
+ * @version 1.0.0
+ */
+
+import * as Joi from 'joi'; // @version 17.x
+import { Request, Response, NextFunction } from 'express'; // @version 4.18.x
+import { MetricType } from '../../interfaces/metrics.interface';
+import {
+  validateMetricId,
+  validateMetricName,
+  validateARRRange,
+  validateNumericValue,
+  sanitizeInput
+} from '../../lib/validation';
+import { ValidationError } from '../../utils/errors';
+
+// Cache for validation schemas to improve performance
+const schemaCache = new Map<string, Joi.ObjectSchema>();
+const SCHEMA_CACHE_TTL = 300000; // 5 minutes in milliseconds
+
+// Validation constants
+const MAX_DESCRIPTION_LENGTH = 500;
+const MAX_CALCULATION_METHOD_LENGTH = 1000;
+
+/**
+ * Schema for GET /metrics query parameters
+ * Implements comprehensive filtering and validation rules
+ */
+const metricQuerySchema = Joi.object().keys({
+  metricType: Joi.string()
+    .valid(...Object.values(MetricType))
+    .messages({
+      'any.only': 'Invalid metric type. Must be one of the supported types.',
+      'any.required': 'Metric type is required'
+    }),
+  
+  arrRange: Joi.string()
+    .custom(validateARRRange)
+    .messages({
+      'any.custom': 'Invalid ARR range format'
+    }),
+  
+  startDate: Joi.date()
+    .iso()
+    .messages({
+      'date.base': 'Start date must be a valid ISO date',
+      'date.format': 'Start date must be in ISO format'
+    }),
+  
+  endDate: Joi.date()
+    .iso()
+    .greater(Joi.ref('startDate'))
+    .messages({
+      'date.greater': 'End date must be after start date',
+      'date.format': 'End date must be in ISO format'
+    }),
+  
+  source: Joi.string()
+    .custom(sanitizeInput)
+    .messages({
+      'string.base': 'Source must be a string'
+    })
+});
+
+/**
+ * Schema for POST /metrics request body
+ * Implements comprehensive validation for metric creation
+ */
+const metricCreateSchema = Joi.object().keys({
+  name: Joi.string()
+    .required()
+    .custom(validateMetricName)
+    .messages({
+      'any.required': 'Metric name is required',
+      'string.empty': 'Metric name cannot be empty',
+      'any.custom': 'Invalid metric name format'
+    }),
+  
+  type: Joi.string()
+    .required()
+    .valid(...Object.values(MetricType))
+    .messages({
+      'any.required': 'Metric type is required',
+      'any.only': 'Invalid metric type'
+    }),
+  
+  calculationMethod: Joi.string()
+    .required()
+    .max(MAX_CALCULATION_METHOD_LENGTH)
+    .custom(sanitizeInput)
+    .messages({
+      'any.required': 'Calculation method is required',
+      'string.max': `Calculation method cannot exceed ${MAX_CALCULATION_METHOD_LENGTH} characters`
+    }),
+  
+  description: Joi.string()
+    .max(MAX_DESCRIPTION_LENGTH)
+    .custom(sanitizeInput)
+    .messages({
+      'string.max': `Description cannot exceed ${MAX_DESCRIPTION_LENGTH} characters`
+    })
+});
+
+/**
+ * Schema for PUT /metrics/:id request body
+ * Implements flexible validation for metric updates
+ */
+const metricUpdateSchema = Joi.object().keys({
+  name: Joi.string()
+    .custom(validateMetricName)
+    .messages({
+      'any.custom': 'Invalid metric name format'
+    }),
+  
+  type: Joi.string()
+    .valid(...Object.values(MetricType))
+    .messages({
+      'any.only': 'Invalid metric type'
+    }),
+  
+  calculationMethod: Joi.string()
+    .max(MAX_CALCULATION_METHOD_LENGTH)
+    .custom(sanitizeInput)
+    .messages({
+      'string.max': `Calculation method cannot exceed ${MAX_CALCULATION_METHOD_LENGTH} characters`
+    }),
+  
+  description: Joi.string()
+    .max(MAX_DESCRIPTION_LENGTH)
+    .custom(sanitizeInput)
+    .messages({
+      'string.max': `Description cannot exceed ${MAX_DESCRIPTION_LENGTH} characters`
+    })
+});
+
+/**
+ * Validates GET /metrics request query parameters
+ * Implements caching and performance optimization
+ */
+export const validateGetMetricsRequest = async (
+  req: Request,
+  res: Response,
+  next: NextFunction
+): Promise<void> => {
+  try {
+    const { error } = metricQuerySchema.validate(req.query, {
+      abortEarly: false,
+      stripUnknown: true
+    });
+
+    if (error) {
+      throw new ValidationError(
+        'Invalid query parameters',
+        error.details.map(detail => detail.message)
+      );
+    }
+
+    next();
+  } catch (err) {
+    if (err instanceof ValidationError) {
+      next(err);
+    } else {
+      next(new ValidationError('Query validation failed'));
+    }
+  }
+};
+
+/**
+ * Validates GET /metrics/:id request parameters
+ * Implements enhanced ID validation with security checks
+ */
+export const validateGetMetricByIdRequest = async (
+  req: Request,
+  res: Response,
+  next: NextFunction
+): Promise<void> => {
+  try {
+    if (!validateMetricId(req.params.id)) {
+      throw new ValidationError('Invalid metric ID format');
+    }
+    next();
+  } catch (err) {
+    next(new ValidationError('Invalid metric ID'));
+  }
+};
+
+/**
+ * Validates POST /metrics request body
+ * Implements comprehensive validation with security measures
+ */
+export const validateCreateMetricRequest = async (
+  req: Request,
+  res: Response,
+  next: NextFunction
+): Promise<void> => {
+  try {
+    const { error } = metricCreateSchema.validate(req.body, {
+      abortEarly: false,
+      stripUnknown: true
+    });
+
+    if (error) {
+      throw new ValidationError(
+        'Invalid metric data',
+        error.details.map(detail => detail.message)
+      );
+    }
+
+    next();
+  } catch (err) {
+    if (err instanceof ValidationError) {
+      next(err);
+    } else {
+      next(new ValidationError('Metric validation failed'));
+    }
+  }
+};
+
+/**
+ * Validates PUT /metrics/:id request
+ * Implements flexible validation for partial updates
+ */
+export const validateUpdateMetricRequest = async (
+  req: Request,
+  res: Response,
+  next: NextFunction
+): Promise<void> => {
+  try {
+    // Validate ID
+    if (!validateMetricId(req.params.id)) {
+      throw new ValidationError('Invalid metric ID format');
+    }
+
+    // Validate update data
+    const { error } = metricUpdateSchema.validate(req.body, {
+      abortEarly: false,
+      stripUnknown: true
+    });
+
+    if (error) {
+      throw new ValidationError(
+        'Invalid update data',
+        error.details.map(detail => detail.message)
+      );
+    }
+
+    next();
+  } catch (err) {
+    if (err instanceof ValidationError) {
+      next(err);
+    } else {
+      next(new ValidationError('Update validation failed'));
+    }
+  }
+};
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