diff --git a/libsquoosh/src/codecs.ts b/libsquoosh/src/codecs.ts
index 98052cd6..0517f217 100644
--- a/libsquoosh/src/codecs.ts
+++ b/libsquoosh/src/codecs.ts
@@ -29,14 +29,23 @@ interface ResizeWithAspectParams {
   target_height: number;
 }
 
-interface ResizeInstantiateOptions {
+export interface ResizeOptions {
   width: number;
   height: number;
-  method: string;
+  method: 'triangle' | 'catrom' | 'mitchell' | 'lanczos3';
   premultiply: boolean;
   linearRGB: boolean;
 }
 
+export interface QuantOptions {
+  numColors: number;
+  dither: number;
+}
+
+export interface RotateOptions {
+  numRotations: number;
+}
+
 declare global {
   // Needed for being able to use ImageData as type in codec types
   type ImageData = import('./image_data.js').default;
@@ -52,6 +61,7 @@ import mozEnc from '../../codecs/mozjpeg/enc/mozjpeg_node_enc.js';
 import mozEncWasm from 'asset-url:../../codecs/mozjpeg/enc/mozjpeg_node_enc.wasm';
 import mozDec from '../../codecs/mozjpeg/dec/mozjpeg_node_dec.js';
 import mozDecWasm from 'asset-url:../../codecs/mozjpeg/dec/mozjpeg_node_dec.wasm';
+import type { EncodeOptions as MozJPEGEncodeOptions } from '../../codecs/mozjpeg/enc/mozjpeg_enc';
 
 // WebP
 import type { WebPModule as WebPEncodeModule } from '../../codecs/webp/enc/webp_enc';
@@ -59,6 +69,7 @@ import webpEnc from '../../codecs/webp/enc/webp_node_enc.js';
 import webpEncWasm from 'asset-url:../../codecs/webp/enc/webp_node_enc.wasm';
 import webpDec from '../../codecs/webp/dec/webp_node_dec.js';
 import webpDecWasm from 'asset-url:../../codecs/webp/dec/webp_node_dec.wasm';
+import type { EncodeOptions as WebPEncodeOptions } from '../../codecs/webp/enc/webp_enc.js';
 
 // AVIF
 import type { AVIFModule as AVIFEncodeModule } from '../../codecs/avif/enc/avif_enc';
@@ -69,6 +80,7 @@ import avifEncMtWorker from 'chunk-url:../../codecs/avif/enc/avif_node_enc_mt.wo
 import avifEncMtWasm from 'asset-url:../../codecs/avif/enc/avif_node_enc_mt.wasm';
 import avifDec from '../../codecs/avif/dec/avif_node_dec.js';
 import avifDecWasm from 'asset-url:../../codecs/avif/dec/avif_node_dec.wasm';
+import type { EncodeOptions as AvifEncodeOptions } from '../../codecs/avif/enc/avif_enc.js';
 
 // JXL
 import type { JXLModule as JXLEncodeModule } from '../../codecs/jxl/enc/jxl_enc';
@@ -76,6 +88,7 @@ import jxlEnc from '../../codecs/jxl/enc/jxl_node_enc.js';
 import jxlEncWasm from 'asset-url:../../codecs/jxl/enc/jxl_node_enc.wasm';
 import jxlDec from '../../codecs/jxl/dec/jxl_node_dec.js';
 import jxlDecWasm from 'asset-url:../../codecs/jxl/dec/jxl_node_dec.wasm';
+import type { EncodeOptions as JxlEncodeOptions } from '../../codecs/jxl/enc/jxl_enc.js';
 
 // WP2
 import type { WP2Module as WP2EncodeModule } from '../../codecs/wp2/enc/wp2_enc';
@@ -83,6 +96,7 @@ import wp2Enc from '../../codecs/wp2/enc/wp2_node_enc.js';
 import wp2EncWasm from 'asset-url:../../codecs/wp2/enc/wp2_node_enc.wasm';
 import wp2Dec from '../../codecs/wp2/dec/wp2_node_dec.js';
 import wp2DecWasm from 'asset-url:../../codecs/wp2/dec/wp2_node_dec.wasm';
+import type { EncodeOptions as WP2EncodeOptions } from '../../codecs/wp2/enc/wp2_enc.js';
 
 // PNG
 import * as pngEncDec from '../../codecs/png/pkg/squoosh_png.js';
@@ -95,6 +109,9 @@ const pngEncDecPromise = pngEncDec.default(
 import * as oxipng from '../../codecs/oxipng/pkg/squoosh_oxipng.js';
 import oxipngWasm from 'asset-url:../../codecs/oxipng/pkg/squoosh_oxipng_bg.wasm';
 const oxipngPromise = oxipng.default(fsp.readFile(pathify(oxipngWasm)));
+interface OxiPngEncodeOptions {
+  level: number;
+}
 
 // Resize
 import * as resize from '../../codecs/resize/pkg/squoosh_resize.js';
@@ -171,13 +188,7 @@ export const preprocessors = {
         buffer: Uint8Array,
         input_width: number,
         input_height: number,
-        {
-          width,
-          height,
-          method,
-          premultiply,
-          linearRGB,
-        }: ResizeInstantiateOptions,
+        { width, height, method, premultiply, linearRGB }: ResizeOptions,
       ) => {
         ({ width, height } = resizeWithAspect({
           input_width,
@@ -218,7 +229,7 @@ export const preprocessors = {
         buffer: Uint8Array,
         width: number,
         height: number,
-        { numColors, dither }: { numColors: number; dither: number },
+        { numColors, dither }: QuantOptions,
       ) =>
         new ImageData(
           imageQuant.quantize(buffer, width, height, numColors, dither),
@@ -239,7 +250,7 @@ export const preprocessors = {
         buffer: Uint8Array,
         width: number,
         height: number,
-        { numRotations }: { numRotations: number },
+        { numRotations }: RotateOptions,
       ) => {
         const degrees = (numRotations * 90) % 360;
         const sameDimensions = degrees == 0 || degrees == 180;
@@ -401,13 +412,13 @@ export const codecs = {
         jxlEncWasm,
       ),
     defaultEncoderOptions: {
-      speed: 4,
+      effort: 1,
       quality: 75,
       progressive: false,
       epf: -1,
-      nearLossless: 0,
       lossyPalette: false,
       decodingSpeedTier: 0,
+      photonNoiseIso: 0,
     },
     autoOptimize: {
       option: 'quality',
@@ -480,3 +491,12 @@ export const codecs = {
     },
   },
 } as const;
+
+export {
+  MozJPEGEncodeOptions,
+  WebPEncodeOptions,
+  AvifEncodeOptions,
+  JxlEncodeOptions,
+  WP2EncodeOptions,
+  OxiPngEncodeOptions,
+};
diff --git a/libsquoosh/src/index.ts b/libsquoosh/src/index.ts
index 48c15091..65c9bec8 100644
--- a/libsquoosh/src/index.ts
+++ b/libsquoosh/src/index.ts
@@ -2,7 +2,19 @@ import { isMainThread } from 'worker_threads';
 import { cpus } from 'os';
 import { promises as fsp } from 'fs';
 
-import { codecs as encoders, preprocessors } from './codecs.js';
+import {
+  AvifEncodeOptions,
+  codecs as encoders,
+  JxlEncodeOptions,
+  MozJPEGEncodeOptions,
+  OxiPngEncodeOptions,
+  preprocessors,
+  QuantOptions,
+  ResizeOptions,
+  RotateOptions,
+  WebPEncodeOptions,
+  WP2EncodeOptions,
+} from './codecs.js';
 import WorkerPool from './worker_pool.js';
 import { autoOptimize } from './auto-optimizer.js';
 import type ImageData from './image_data';
@@ -12,6 +24,12 @@ type EncoderKey = keyof typeof encoders;
 type PreprocessorKey = keyof typeof preprocessors;
 type FileLike = Buffer | ArrayBuffer | string | ArrayBufferView;
 
+type PreprocessOptions = {
+  resize?: ResizeOptions;
+  quant?: QuantOptions;
+  rotate?: RotateOptions;
+};
+
 async function decodeFile({
   file,
 }: {
@@ -183,10 +201,10 @@ class Image {
 
   /**
    * Define one or several preprocessors to use on the image.
-   * @param {object} preprocessOptions - An object with preprocessors to use, and their settings.
+   * @param {PreprocessOptions} preprocessOptions - An object with preprocessors to use, and their settings.
    * @returns {Promise<undefined>} - A promise that resolves when all preprocessors have completed their work.
    */
-  async preprocess(preprocessOptions = {}) {
+  async preprocess(preprocessOptions: PreprocessOptions = {}) {
     for (const [name, options] of Object.entries(preprocessOptions)) {
       if (!Object.keys(preprocessors).includes(name)) {
         throw Error(`Invalid preprocessor "${name}"`);
@@ -217,7 +235,12 @@ class Image {
       optimizerButteraugliTarget?: number;
       maxOptimizerRounds?: number;
     } & {
-      [key in EncoderKey]?: any; // any is okay for now
+      mozjpeg?: Partial<MozJPEGEncodeOptions>;
+      webp?: Partial<WebPEncodeOptions>;
+      avif?: Partial<AvifEncodeOptions>;
+      jxl?: Partial<JxlEncodeOptions>;
+      wp2?: Partial<WP2EncodeOptions>;
+      oxipng?: Partial<OxiPngEncodeOptions>;
     } = {},
   ): Promise<void> {
     const { bitmap } = await this.decoded;