diff --git a/src/index.ts b/src/index.ts
index c769e99..9a1c16d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -227,6 +227,10 @@ export async function listModels(options: Omit<ListModelsOptions, 'budgetManager
 
 // Keep the original export for backward compatibility
 export { listAvailableModels };
+export {
+  DEFAULT_KEYWORD_TASKS,
+  detectByKeywords
+} from "./router/keywordDetector";
 
 // Export types for TypeScript users
 export type {
@@ -252,6 +256,12 @@ export type {
   ApiKeyConfig
 } from "./router/types";
 
+export type {
+  KeywordDetectionOptions,
+  KeywordDetectionResult,
+  KeywordTaskDefinition
+} from "./router/keywordDetector";
+
 /**
  * Model configuration for bulk registration
  */
diff --git a/src/router/keywordDetector.ts b/src/router/keywordDetector.ts
new file mode 100644
index 0000000..2bffb50
--- /dev/null
+++ b/src/router/keywordDetector.ts
@@ -0,0 +1,153 @@
+export interface KeywordTaskDefinition {
+  taskType: string;
+  keywords: string[];
+  model: string;
+  reason: string;
+}
+
+export interface KeywordDetectionOptions {
+  taskDefinitions?: KeywordTaskDefinition[];
+  maxPromptLength?: number;
+  minimumConfidence?: number;
+}
+
+export interface KeywordDetectionResult {
+  taskType: string;
+  confidence: number;
+  selectedModel: string;
+  reason: string;
+  matchedKeywords: string[];
+}
+
+const DEFAULT_MAX_PROMPT_LENGTH = 20_000;
+const DEFAULT_MINIMUM_CONFIDENCE = 0.18;
+
+export const DEFAULT_KEYWORD_TASKS: KeywordTaskDefinition[] = [
+  {
+    taskType: "code_generation",
+    keywords: ["write code", "create function", "implement", "build api", "develop", "program"],
+    model: "claude-3-5-sonnet-20241022",
+    reason: "Claude is preferred for implementation and code generation tasks"
+  },
+  {
+    taskType: "code_review",
+    keywords: ["review code", "find bugs", "debug", "refactor", "optimize code", "security review"],
+    model: "claude-3-5-sonnet-20241022",
+    reason: "Claude is preferred for code review and refactoring tasks"
+  },
+  {
+    taskType: "math_reasoning",
+    keywords: ["calculate", "solve equation", "formula", "derivative", "probability", "math"],
+    model: "o1-mini",
+    reason: "o1-mini is preferred for math and calculation tasks"
+  },
+  {
+    taskType: "complex_reasoning",
+    keywords: ["reason step by step", "deduce", "prove", "logic puzzle", "analyze tradeoff", "root cause"],
+    model: "o1",
+    reason: "o1 is preferred for complex reasoning and logic tasks"
+  },
+  {
+    taskType: "document_analysis",
+    keywords: ["summarize document", "analyze document", "extract from", "research paper", "contract", "pdf"],
+    model: "gemini-2.5-pro",
+    reason: "Gemini is preferred for long document analysis"
+  },
+  {
+    taskType: "creative_writing",
+    keywords: ["write story", "blog post", "creative", "copywriting", "product description", "tone"],
+    model: "gpt-4o",
+    reason: "GPT-4o is preferred for creative writing tasks"
+  },
+  {
+    taskType: "translation",
+    keywords: ["translate", "translation", "convert to spanish", "convert to french", "localize"],
+    model: "gpt-4o-mini",
+    reason: "GPT-4o mini is preferred for lightweight translation tasks"
+  },
+  {
+    taskType: "simple_chat",
+    keywords: ["hello", "thanks", "quick question", "explain simply", "what is"],
+    model: "gpt-4o-mini",
+    reason: "GPT-4o mini is preferred for lightweight chat tasks"
+  },
+  {
+    taskType: "data_extraction",
+    keywords: ["extract data", "parse json", "structured output", "csv", "table", "fields"],
+    model: "gpt-4o-mini",
+    reason: "GPT-4o mini is preferred for structured extraction tasks"
+  },
+  {
+    taskType: "chinese_language",
+    keywords: ["chinese", "mandarin", "中文", "汉语", "翻译成中文"],
+    model: "moonshot-v1-32k",
+    reason: "Kimi is preferred for Chinese language tasks"
+  }
+];
+
+/**
+ * Detect the likely task type by matching documented smart-routing keywords.
+ */
+export function detectByKeywords(
+  prompt: string,
+  options: KeywordDetectionOptions = {}
+): KeywordDetectionResult | null {
+  if (typeof prompt !== "string" || prompt.trim() === "") {
+    return null;
+  }
+
+  const maxPromptLength = options.maxPromptLength ?? DEFAULT_MAX_PROMPT_LENGTH;
+  const minimumConfidence = options.minimumConfidence ?? DEFAULT_MINIMUM_CONFIDENCE;
+  const normalizedPrompt = normalizePrompt(prompt.slice(0, maxPromptLength));
+  const taskDefinitions = options.taskDefinitions ?? DEFAULT_KEYWORD_TASKS;
+
+  let bestResult: KeywordDetectionResult | null = null;
+
+  for (const definition of taskDefinitions) {
+    const matchedKeywords = getMatchedKeywords(normalizedPrompt, definition.keywords);
+    if (matchedKeywords.length === 0) {
+      continue;
+    }
+
+    const confidence = calculateConfidence(matchedKeywords, definition.keywords.length);
+    if (confidence < minimumConfidence) {
+      continue;
+    }
+
+    if (!bestResult || confidence > bestResult.confidence) {
+      bestResult = {
+        taskType: definition.taskType,
+        confidence,
+        selectedModel: definition.model,
+        reason: definition.reason,
+        matchedKeywords
+      };
+    }
+  }
+
+  return bestResult;
+}
+
+function normalizePrompt(prompt: string): string {
+  return prompt.toLowerCase().replace(/\s+/g, " ");
+}
+
+function getMatchedKeywords(prompt: string, keywords: string[]): string[] {
+  const seen = new Set<string>();
+  return keywords
+    .map((keyword) => keyword.trim().toLowerCase())
+    .filter(Boolean)
+    .filter((keyword) => {
+      if (seen.has(keyword) || !prompt.includes(keyword)) {
+        return false;
+      }
+      seen.add(keyword);
+      return true;
+    });
+}
+
+function calculateConfidence(matchedKeywords: string[], totalKeywords: number): number {
+  const coverage = matchedKeywords.length / Math.max(totalKeywords, 1);
+  const matchBoost = Math.min(matchedKeywords.length * 0.16, 0.64);
+  return Number(Math.min(0.95, 0.2 + coverage * 0.45 + matchBoost).toFixed(2));
+}
diff --git a/tests/keyword-detector.test.js b/tests/keyword-detector.test.js
new file mode 100644
index 0000000..56dfbf8
--- /dev/null
+++ b/tests/keyword-detector.test.js
@@ -0,0 +1,58 @@
+/**
+ * Keyword detector tests.
+ *
+ * Run: node tests/keyword-detector.test.js
+ */
+
+const { detectByKeywords } = require("../dist/index.js");
+
+function assert(condition, message) {
+  if (!condition) {
+    throw new Error(message);
+  }
+}
+
+try {
+  const codeResult = detectByKeywords("Please write code to implement a REST API endpoint");
+  assert(codeResult, "code generation prompt should be classified");
+  assert(codeResult.taskType === "code_generation", "should detect code_generation");
+  assert(codeResult.selectedModel === "claude-3-5-sonnet-20241022", "should recommend Claude for code");
+  assert(codeResult.confidence >= 0.5, "code confidence should include multiple keyword matches");
+  assert(codeResult.matchedKeywords.includes("write code"), "should report matched keyword");
+
+  const mathResult = detectByKeywords("Can you solve equation x^2 + 2x and calculate the roots?");
+  assert(mathResult, "math prompt should be classified");
+  assert(mathResult.taskType === "math_reasoning", "should detect math_reasoning");
+  assert(mathResult.selectedModel === "o1-mini", "should recommend o1-mini for math");
+
+  const customResult = detectByKeywords("route this urgent support ticket", {
+    taskDefinitions: [
+      {
+        taskType: "support_triage",
+        keywords: ["urgent support", "ticket"],
+        model: "gpt-4o-mini",
+        reason: "Support triage is lightweight"
+      }
+    ]
+  });
+  assert(customResult, "custom keyword definitions should be supported");
+  assert(customResult.taskType === "support_triage", "should classify custom task type");
+  assert(customResult.matchedKeywords.length === 2, "should return custom keyword matches");
+
+  const ignoredResult = detectByKeywords("hello", {
+    minimumConfidence: 0.9
+  });
+  assert(ignoredResult === null, "minimumConfidence should filter weak matches");
+
+  const emptyResult = detectByKeywords("   ");
+  assert(emptyResult === null, "empty prompts should not classify");
+
+  const longPrompt = `${"noise ".repeat(5000)} write code`;
+  const boundedResult = detectByKeywords(longPrompt, { maxPromptLength: 100 });
+  assert(boundedResult === null, "maxPromptLength should bound scanning");
+
+  console.log("Keyword detector tests passed.");
+} catch (error) {
+  console.error("Keyword detector tests failed:", error.message);
+  process.exit(1);
+}