diff --git a/nats-base-client/authenticator.ts b/nats-base-client/authenticator.ts
index 535f297a..9df7ee41 100644
--- a/nats-base-client/authenticator.ts
+++ b/nats-base-client/authenticator.ts
@@ -14,17 +14,16 @@
  */
 import { nkeys } from "./nkeys.ts";
 import { TD, TE } from "./encoders.ts";
-import {
+import type {
   Auth,
   Authenticator,
-  ErrorCode,
   JwtAuth,
-  NatsError,
   NKeyAuth,
   NoAuth,
   TokenAuth,
   UserPass,
 } from "./core.ts";
+import { ErrorCode, NatsError } from "./core.ts";
 
 export function multiAuthenticator(authenticators: Authenticator[]) {
   return (nonce?: string): Auth => {
diff --git a/nats-base-client/bench.ts b/nats-base-client/bench.ts
index d0e93227..de15d34c 100644
--- a/nats-base-client/bench.ts
+++ b/nats-base-client/bench.ts
@@ -17,7 +17,8 @@ import { Empty } from "./types.ts";
 import { nuid } from "./nuid.ts";
 import { deferred, Perf } from "./util.ts";
 import type { NatsConnectionImpl } from "./nats.ts";
-import { ErrorCode, NatsConnection, NatsError } from "./core.ts";
+import { ErrorCode, NatsError } from "./core.ts";
+import type { NatsConnection } from "./core.ts";
 
 export class Metric {
   name: string;
diff --git a/nats-base-client/core.ts b/nats-base-client/core.ts
index 35b9dc36..51f89aa1 100644
--- a/nats-base-client/core.ts
+++ b/nats-base-client/core.ts
@@ -194,6 +194,8 @@ export class NatsError extends Error {
   }
 }
 
+export type MsgCallback<T> = (err: NatsError | null, msg: T) => void;
+
 /**
  * Subscription Options
  */
@@ -221,7 +223,7 @@ export interface SubOpts<T> {
    * @param err
    * @param msg
    */
-  callback?: (err: NatsError | null, msg: T) => void;
+  callback?: MsgCallback<T>;
 }
 
 export interface DnsResolveFn {
diff --git a/nats-base-client/deno.json b/nats-base-client/deno.json
index 79920d36..ddcda428 100644
--- a/nats-base-client/deno.json
+++ b/nats-base-client/deno.json
@@ -2,12 +2,15 @@
   "name": "@nats-io/nats-core",
   "version": "3.0.0-1",
   "exports": {
-    ".": "./src/mod.ts"
+    ".": "./mod.ts",
+    "./internal": "./internal_mod.ts"
   },
   "publish": {
     "include": [
-      "./src/**/*",
-      "jsr.json"
+      "./**/*"
     ]
+  },
+  "imports": {
+    "jsr:@nats-io/nkeys": "jsr:@nats-io/nkeys@1.1.1-1"
   }
 }
diff --git a/nats-base-client/encoders.ts b/nats-base-client/encoders.ts
index d5a49444..8dd989f2 100644
--- a/nats-base-client/encoders.ts
+++ b/nats-base-client/encoders.ts
@@ -12,10 +12,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-export const Empty = new Uint8Array(0);
+export const Empty: Uint8Array = new Uint8Array(0);
 
-export const TE = new TextEncoder();
-export const TD = new TextDecoder();
+export const TE: TextEncoder = new TextEncoder();
+export const TD: TextDecoder = new TextDecoder();
 
 function concat(...bufs: Uint8Array[]): Uint8Array {
   let max = 0;
diff --git a/nats-base-client/headers.ts b/nats-base-client/headers.ts
index 815ab4a7..07fddbc3 100644
--- a/nats-base-client/headers.ts
+++ b/nats-base-client/headers.ts
@@ -16,7 +16,8 @@
 // Heavily inspired by Golang's https://golang.org/src/net/http/header.go
 
 import { TD, TE } from "./encoders.ts";
-import { ErrorCode, Match, MsgHdrs, NatsError } from "./core.ts";
+import type { MsgHdrs } from "./core.ts";
+import { ErrorCode, Match, NatsError } from "./core.ts";
 
 // https://www.ietf.org/rfc/rfc822.txt
 // 3.1.2.  STRUCTURE OF HEADER FIELDS
@@ -82,7 +83,7 @@ export class MsgHdrsImpl implements MsgHdrs {
     this.headers = new Map();
   }
 
-  [Symbol.iterator]() {
+  [Symbol.iterator](): IterableIterator<[string, string[]]> {
     return this.headers.entries();
   }
 
@@ -276,7 +277,7 @@ export class MsgHdrsImpl implements MsgHdrs {
     });
   }
 
-  get hasError() {
+  get hasError(): boolean {
     return this._code >= 300;
   }
 
diff --git a/nats-base-client/heartbeats.ts b/nats-base-client/heartbeats.ts
index e32ef9be..2a56b7a5 100644
--- a/nats-base-client/heartbeats.ts
+++ b/nats-base-client/heartbeats.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 The NATS Authors
+ * Copyright 2020-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -12,9 +12,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { Deferred, deferred } from "./util.ts";
 
-import { DebugEvents, Status } from "./core.ts";
+import type { Deferred } from "./util.ts";
+import { deferred } from "./util.ts";
+import type { Status } from "./core.ts";
+import { DebugEvents } from "./core.ts";
 
 export interface PH {
   flush(p?: Deferred<void>): Promise<void>;
diff --git a/nats-base-client/ipparser.ts b/nats-base-client/ipparser.ts
index f9ca7e83..6082ded3 100644
--- a/nats-base-client/ipparser.ts
+++ b/nats-base-client/ipparser.ts
@@ -43,7 +43,7 @@ export function ipV4(a: number, b: number, c: number, d: number): Uint8Array {
   return ip;
 }
 
-export function isIP(h: string) {
+export function isIP(h: string): boolean {
   return parseIP(h) !== undefined;
 }
 
diff --git a/nats-base-client/msg.ts b/nats-base-client/msg.ts
index 8193554e..6598cf86 100644
--- a/nats-base-client/msg.ts
+++ b/nats-base-client/msg.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2023 The NATS Authors
+ * Copyright 2020-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -15,16 +15,16 @@
 import { MsgHdrsImpl } from "./headers.ts";
 import type { MsgArg } from "./parser.ts";
 import { Empty, TD } from "./encoders.ts";
-import { Codec, JSONCodec } from "./codec.ts";
-import {
-  ErrorCode,
+import type { Codec } from "./codec.ts";
+import { JSONCodec } from "./codec.ts";
+import type {
   Msg,
   MsgHdrs,
-  NatsError,
   Publisher,
   RequestInfo,
   ReviverFn,
 } from "./core.ts";
+import { ErrorCode, NatsError } from "./core.ts";
 
 export function isRequestError(msg: Msg): NatsError | null {
   // NATS core only considers errors 503s on messages that have no payload
diff --git a/nats-base-client/muxsubscription.ts b/nats-base-client/muxsubscription.ts
index 5ce3ffbf..f49bef73 100644
--- a/nats-base-client/muxsubscription.ts
+++ b/nats-base-client/muxsubscription.ts
@@ -13,7 +13,8 @@
  * limitations under the License.
  */
 import { isRequestError } from "./msg.ts";
-import { createInbox, ErrorCode, Msg, NatsError, Request } from "./core.ts";
+import type { Msg, MsgCallback, Request } from "./core.ts";
+import { createInbox, ErrorCode, NatsError } from "./core.ts";
 
 export class MuxSubscription {
   baseInbox!: string;
@@ -82,7 +83,7 @@ export class MuxSubscription {
     return false;
   }
 
-  dispatcher() {
+  dispatcher(): MsgCallback<Msg> {
     return (err: NatsError | null, m: Msg) => {
       const token = this.getToken(m);
       if (token) {
diff --git a/nats-base-client/nats.ts b/nats-base-client/nats.ts
index caef8363..9f4bdce0 100644
--- a/nats-base-client/nats.ts
+++ b/nats-base-client/nats.ts
@@ -18,22 +18,21 @@ import { ProtocolHandler, SubscriptionImpl } from "./protocol.ts";
 import { Empty } from "./encoders.ts";
 import { NatsError } from "./types.ts";
 
-import type { SemVer } from "./semver.ts";
-import { Features, parseSemVer } from "./semver.ts";
+import type { Features, SemVer } from "./semver.ts";
+import { parseSemVer } from "./semver.ts";
 
 import { parseOptions } from "./options.ts";
 import { QueuedIteratorImpl } from "./queued_iterator.ts";
-import {
-  RequestMany,
-  RequestManyOptionsInternal,
-  RequestOne,
-} from "./request.ts";
+import { RequestMany, RequestOne } from "./request.ts";
+
+import type { RequestManyOptionsInternal } from "./request.ts";
+
 import { isRequestError } from "./msg.ts";
-import {
+import { createInbox, ErrorCode, RequestStrategy } from "./core.ts";
+
+import type {
   ConnectionOptions,
   Context,
-  createInbox,
-  ErrorCode,
   Msg,
   NatsConnection,
   Payload,
@@ -41,7 +40,6 @@ import {
   QueuedIterator,
   RequestManyOptions,
   RequestOptions,
-  RequestStrategy,
   ServerInfo,
   Stats,
   Status,
@@ -115,14 +113,14 @@ export class NatsConnectionImpl implements NatsConnection {
     this.protocol.publish(subject, data, options);
   }
 
-  publishMessage(msg: Msg) {
+  publishMessage(msg: Msg): void {
     return this.publish(msg.subject, msg.data, {
       reply: msg.reply,
       headers: msg.headers,
     });
   }
 
-  respondMessage(msg: Msg) {
+  respondMessage(msg: Msg): boolean {
     if (msg.reply) {
       this.publish(msg.reply, msg.data, {
         reply: msg.reply,
diff --git a/nats-base-client/nkeys.ts b/nats-base-client/nkeys.ts
index fe97cc84..3f33d2c6 100644
--- a/nats-base-client/nkeys.ts
+++ b/nats-base-client/nkeys.ts
@@ -1 +1 @@
-export * as nkeys from "https://raw.githubusercontent.com/nats-io/nkeys.js/v1.0.4/modules/esm/mod.ts";
+export * as nkeys from "jsr:@nats-io/nkeys";
diff --git a/nats-base-client/options.ts b/nats-base-client/options.ts
index daea87d3..fb8ab7eb 100644
--- a/nats-base-client/options.ts
+++ b/nats-base-client/options.ts
@@ -15,20 +15,14 @@
 
 import { extend } from "./util.ts";
 import { defaultPort, getResolveFn } from "./transport.ts";
-import { createInbox, ServerInfo } from "./core.ts";
+import type { Authenticator, ConnectionOptions, ServerInfo } from "./core.ts";
+import { createInbox, DEFAULT_HOST, ErrorCode, NatsError } from "./core.ts";
 import {
   multiAuthenticator,
   noAuthFn,
   tokenAuthenticator,
   usernamePasswordAuthenticator,
 } from "./authenticator.ts";
-import {
-  Authenticator,
-  ConnectionOptions,
-  DEFAULT_HOST,
-  ErrorCode,
-  NatsError,
-} from "./core.ts";
 
 export const DEFAULT_MAX_RECONNECT_ATTEMPTS = 10;
 export const DEFAULT_JITTER = 100;
diff --git a/nats-base-client/parser.ts b/nats-base-client/parser.ts
index f8747fc0..550a9f00 100644
--- a/nats-base-client/parser.ts
+++ b/nats-base-client/parser.ts
@@ -15,7 +15,7 @@
  */
 import { DenoBuffer } from "./denobuffer.ts";
 import { TD } from "./encoders.ts";
-import { Dispatcher } from "./core.ts";
+import type { Dispatcher } from "./core.ts";
 
 export enum Kind {
   OK,
diff --git a/nats-base-client/protocol.ts b/nats-base-client/protocol.ts
index 58bd4761..0fd3910b 100644
--- a/nats-base-client/protocol.ts
+++ b/nats-base-client/protocol.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2023 The NATS Authors
+ * Copyright 2018-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -13,38 +13,35 @@
  * limitations under the License.
  */
 import { decode, Empty, encode, TE } from "./encoders.ts";
-import {
-  CR_LF,
-  CRLF,
-  getResolveFn,
-  newTransport,
-  Transport,
-} from "./transport.ts";
-import { Deferred, deferred, delay, extend, Timeout, timeout } from "./util.ts";
+import { CR_LF, CRLF, getResolveFn, newTransport } from "./transport.ts";
+import type { Transport } from "./transport.ts";
+import { deferred, delay, extend, timeout } from "./util.ts";
+import type { Deferred, Timeout } from "./util.ts";
 import { DataBuffer } from "./databuffer.ts";
-import { ServerImpl, Servers } from "./servers.ts";
-import {
+import { Servers } from "./servers.ts";
+import type { ServerImpl } from "./servers.ts";
+import type {
   DispatchedFn,
   IngestionFilterFn,
   IngestionFilterFnResult,
   ProtocolFilterFn,
-  QueuedIteratorImpl,
 } from "./queued_iterator.ts";
+import { QueuedIteratorImpl } from "./queued_iterator.ts";
 import type { MsgHdrsImpl } from "./headers.ts";
 import { MuxSubscription } from "./muxsubscription.ts";
-import { Heartbeat, PH } from "./heartbeats.ts";
-import { Kind, MsgArg, Parser, ParserEvent } from "./parser.ts";
+import { Heartbeat } from "./heartbeats.ts";
+import type { PH } from "./heartbeats.ts";
+import type { MsgArg, ParserEvent } from "./parser.ts";
+import { Kind, Parser } from "./parser.ts";
 import { MsgImpl } from "./msg.ts";
 import { Features, parseSemVer } from "./semver.ts";
-import {
+import { DebugEvents, ErrorCode, Events, NatsError } from "./core.ts";
+
+import type {
   Base,
   ConnectionOptions,
-  DebugEvents,
   Dispatcher,
-  ErrorCode,
-  Events,
   Msg,
-  NatsError,
   Payload,
   Publisher,
   PublishOptions,
@@ -56,6 +53,7 @@ import {
   Subscription,
   SubscriptionOptions,
 } from "./core.ts";
+
 import {
   DEFAULT_MAX_PING_OUT,
   DEFAULT_PING_INTERVAL,
@@ -691,7 +689,7 @@ export class ProtocolHandler implements Dispatcher<ParserEvent> {
     return h;
   }
 
-  static toError(s: string) {
+  static toError(s: string): NatsError {
     const t = s ? s.toLowerCase() : "";
     if (t.indexOf("permissions violation") !== -1) {
       const err = new NatsError(s, ErrorCode.PermissionsViolation);
@@ -964,7 +962,7 @@ export class ProtocolHandler implements Dispatcher<ParserEvent> {
     }
   }
 
-  _subunsub(s: SubscriptionImpl) {
+  _subunsub(s: SubscriptionImpl): SubscriptionImpl {
     this._sub(s);
     if (s.max) {
       this.unsubscribe(s, s.max);
diff --git a/nats-base-client/queued_iterator.ts b/nats-base-client/queued_iterator.ts
index dc26d292..17793510 100644
--- a/nats-base-client/queued_iterator.ts
+++ b/nats-base-client/queued_iterator.ts
@@ -12,8 +12,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { Deferred, deferred } from "./util.ts";
-import { ErrorCode, NatsError, QueuedIterator } from "./core.ts";
+import type { Deferred } from "./util.ts";
+import { deferred } from "./util.ts";
+import type { QueuedIterator } from "./core.ts";
+import { ErrorCode, NatsError } from "./core.ts";
 
 export type IngestionFilterFnResult = { ingest: boolean; protocol: boolean };
 
@@ -83,7 +85,7 @@ export class QueuedIteratorImpl<T> implements QueuedIterator<T> {
     this.yielding = false;
   }
 
-  [Symbol.asyncIterator]() {
+  [Symbol.asyncIterator](): AsyncIterator<T> {
     return this.iterate();
   }
 
diff --git a/nats-base-client/request.ts b/nats-base-client/request.ts
index 7cc77333..97579224 100644
--- a/nats-base-client/request.ts
+++ b/nats-base-client/request.ts
@@ -12,18 +12,17 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { Deferred, deferred, Timeout, timeout } from "./util.ts";
-import { MuxSubscription } from "./muxsubscription.ts";
+import type { Deferred, Timeout } from "./util.ts";
+import { deferred, timeout } from "./util.ts";
+import type { MuxSubscription } from "./muxsubscription.ts";
 import { nuid } from "./nuid.ts";
-import {
-  ErrorCode,
+import type {
   Msg,
-  NatsError,
   Request,
   RequestManyOptions,
   RequestOptions,
-  RequestStrategy,
 } from "./core.ts";
+import { ErrorCode, NatsError, RequestStrategy } from "./core.ts";
 
 export class BaseRequest {
   token: string;
diff --git a/nats-base-client/semver.ts b/nats-base-client/semver.ts
index 65706ab3..8bb95280 100644
--- a/nats-base-client/semver.ts
+++ b/nats-base-client/semver.ts
@@ -73,7 +73,7 @@ export class Features {
   /**
    * Removes all disabled entries
    */
-  resetDisabled() {
+  resetDisabled(): void {
     this.disabled.length = 0;
     this.update(this.server);
   }
@@ -82,16 +82,16 @@ export class Features {
    * Disables a particular feature.
    * @param f
    */
-  disable(f: Feature) {
+  disable(f: Feature): void {
     this.disabled.push(f);
     this.update(this.server);
   }
 
-  isDisabled(f: Feature) {
+  isDisabled(f: Feature): boolean {
     return this.disabled.indexOf(f) !== -1;
   }
 
-  update(v: SemVer | string) {
+  update(v: SemVer | string): void {
     if (typeof v === "string") {
       v = parseSemVer(v);
     }
@@ -122,7 +122,7 @@ export class Features {
    * @param f
    * @param requires
    */
-  set(f: Feature, requires: string) {
+  set(f: Feature, requires: string): void {
     this.features.set(f, {
       min: requires,
       ok: compare(this.server, parseSemVer(requires)) >= 0,
diff --git a/nats-base-client/servers.ts b/nats-base-client/servers.ts
index e7c28205..8aa22f36 100644
--- a/nats-base-client/servers.ts
+++ b/nats-base-client/servers.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2022 The NATS Authors
+ * Copyright 2018-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -15,14 +15,13 @@
 import { defaultPort, getUrlParseFn } from "./transport.ts";
 import { shuffle } from "./util.ts";
 import { isIP } from "./ipparser.ts";
-import {
-  DEFAULT_HOST,
-  DEFAULT_PORT,
+import type {
   DnsResolveFn,
   Server,
   ServerInfo,
   ServersChanged,
 } from "./core.ts";
+import { DEFAULT_HOST, DEFAULT_PORT } from "./core.ts";
 
 export function isIPV4OrHostname(hp: string): boolean {
   if (hp.indexOf(".") !== -1) {
diff --git a/nats-base-client/transport.ts b/nats-base-client/transport.ts
index 8466b294..9007889f 100644
--- a/nats-base-client/transport.ts
+++ b/nats-base-client/transport.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 The NATS Authors
+ * Copyright 2020-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -14,13 +14,14 @@
  */
 import { TD } from "./encoders.ts";
 
-import {
+import type {
   ConnectionOptions,
-  DEFAULT_PORT,
   DnsResolveFn,
   Server,
   URLParseFn,
 } from "./core.ts";
+
+import { DEFAULT_PORT } from "./core.ts";
 import { DataBuffer } from "./databuffer.ts";
 
 let transportConfig: TransportFactory;
diff --git a/nats-base-client/typedsub.ts b/nats-base-client/typedsub.ts
index 56766c2e..09e55555 100644
--- a/nats-base-client/typedsub.ts
+++ b/nats-base-client/typedsub.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 The NATS Authors
+ * Copyright 2021-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -12,25 +12,24 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-import { Deferred, deferred } from "./util.ts";
+import type { Deferred } from "./util.ts";
+import { deferred } from "./util.ts";
 import type {
   DispatchedFn,
   IngestionFilterFn,
   ProtocolFilterFn,
 } from "./queued_iterator.ts";
 import { QueuedIteratorImpl } from "./queued_iterator.ts";
-import {
-  ErrorCode,
+import type {
   Msg,
   NatsConnection,
-  NatsError,
   Sub,
   SubOpts,
   Subscription,
   SubscriptionOptions,
 } from "./core.ts";
-import { SubscriptionImpl } from "./protocol.ts";
+import { ErrorCode, NatsError } from "./core.ts";
+import type { SubscriptionImpl } from "./protocol.ts";
 
 /**
  * Converts a NATS message into some other type. Implementers are expected to:
diff --git a/nats-base-client/util.ts b/nats-base-client/util.ts
index c69fc933..d4de3d5c 100644
--- a/nats-base-client/util.ts
+++ b/nats-base-client/util.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2023 The NATS Authors
+ * Copyright 2018-2024 The NATS Authors
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -14,7 +14,8 @@
  */
 // deno-lint-ignore-file no-explicit-any
 import { TD } from "./encoders.ts";
-import { ErrorCode, Nanos, NatsError } from "./core.ts";
+import type { Nanos } from "./core.ts";
+import { ErrorCode, NatsError } from "./core.ts";
 
 export type ValueResult<T> = {
   isError: false;
@@ -298,6 +299,6 @@ export function nanos(millis: number): Nanos {
  * Convert the specified Nanos into millis
  * @param ns
  */
-export function millis(ns: Nanos) {
+export function millis(ns: Nanos): number {
   return Math.floor(ns / 1000000);
 }