diff --git a/src/server.ts b/src/server.ts
index be0aa13..0fa653f 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -12,6 +12,7 @@ import { handleInfoPage } from "./info-page";
 import { logQueue } from "./prompt-logging";
 import { start as startRequestQueue } from "./proxy/queue";
 import { init as initUserStore } from "./proxy/auth/user-store";
+import { init as initTokenizers } from "./tokenization";
 import { checkOrigin } from "./proxy/check-origin";
 
 const PORT = config.port;
@@ -99,6 +100,8 @@ async function start() {
 
   keyPool.init();
 
+  await initTokenizers();
+
   if (config.gatekeeper === "user_token") {
     await initUserStore();
   }
diff --git a/src/tokenization/index.ts b/src/tokenization/index.ts
new file mode 100644
index 0000000..2d07f5e
--- /dev/null
+++ b/src/tokenization/index.ts
@@ -0,0 +1 @@
+export { init, countTokens } from "./tokenizer";
diff --git a/src/tokenization/openai.ts b/src/tokenization/openai.ts
new file mode 100644
index 0000000..e226e82
--- /dev/null
+++ b/src/tokenization/openai.ts
@@ -0,0 +1,18 @@
+import { Tiktoken } from "tiktoken/lite";
+import cl100k_base from "tiktoken/encoders/cl100k_base.json";
+
+let encoder: Tiktoken;
+
+export function init() {
+  encoder = new Tiktoken(
+    cl100k_base.bpe_ranks,
+    cl100k_base.special_tokens,
+    cl100k_base.pat_str
+  );
+  return true;
+}
+
+export function getTokenCount(text: string) {
+  const tokens = encoder.encode(text);
+  return tokens.length;
+}
diff --git a/src/tokenization/tokenizer.ts b/src/tokenization/tokenizer.ts
new file mode 100644
index 0000000..cf55659
--- /dev/null
+++ b/src/tokenization/tokenizer.ts
@@ -0,0 +1,65 @@
+import { Request } from "express";
+import { config } from "../config";
+import { AIService } from "../key-management";
+import { logger } from "../logger";
+import {
+  init as initIpc,
+  requestTokenCount as requestClaudeTokenCount,
+} from "./claude-ipc";
+import {
+  init as initEncoder,
+  getTokenCount as getOpenAITokenCount,
+} from "./openai";
+
+let canTokenizeClaude = false;
+let canTokenizeOpenAI = false;
+
+export async function init() {
+  if (config.anthropicKey) {
+    canTokenizeClaude = await initIpc();
+    if (!canTokenizeClaude) {
+      logger.warn(
+        "Anthropic key is set, but tokenizer is not available. Claude prompts will use a naive estimate for token count."
+      );
+    }
+  }
+  if (config.openaiKey) {
+    canTokenizeOpenAI = initEncoder();
+  }
+}
+
+export async function countTokens({
+  req,
+  prompt,
+  service,
+}: {
+  req: Request;
+  prompt: string;
+  service: AIService;
+}) {
+  if (service === "anthropic") {
+    if (!canTokenizeClaude) return guesstimateClaudeTokenCount(prompt);
+    try {
+      return await requestClaudeTokenCount({
+        requestId: String(req.id),
+        prompt: prompt,
+      });
+    } catch (e) {
+      req.log.error("Failed to tokenize with claude_tokenizer", e);
+      return guesstimateClaudeTokenCount(prompt);
+    }
+  }
+  if (service === "openai") {
+    // All OpenAI models we support use the same tokenizer currently
+    return getOpenAITokenCount(prompt);
+  }
+}
+
+function guesstimateClaudeTokenCount(prompt: string) {
+  // From Anthropic's docs:
+  // The maximum length of prompt that Claude can see is its context window.
+  // Claude's context window is currently ~6500 words / ~8000 tokens /
+  // ~28000 Unicode characters.
+  // We'll round up to ~0.3 tokens per character
+  return Math.ceil(prompt.length * 0.3);
+}