diff --git a/src/common/file.ts b/src/common/file/browser.ts
similarity index 84%
rename from src/common/file.ts
rename to src/common/file/browser.ts
index 9365725..529f7a3 100644
--- a/src/common/file.ts
+++ b/src/common/file/browser.ts
@@ -1,7 +1,7 @@
 /*
 
-Common file processing functions
-================================
+File processing functions for the browser
+=========================================
 
 Copyright (c) 2024 Dannii Willis
 MIT licenced
@@ -11,23 +11,7 @@ https://github.com/curiousdannii/asyncglk
 
 import {gunzipSync} from 'fflate'
 
-export type ProgressCallback = (bytes: number) => void
-
-export type TruthyOption = boolean | number
-
-export interface DownloadOptions {
-    /** Domains to access directly: should always have both Access-Control-Allow-Origin and compression headers */
-    direct_domains?: string[],
-    /** Path to resources */
-    lib_path?: string,
-    /** URL of Proxy */
-    proxy_url?: string,
-    /** Whether to load embedded resources in single file mode */
-    single_file?: TruthyOption,
-    /** Use the file proxy; if disabled may mean that some files can't be loaded */
-    // We could just say to exclude proxy_url instead?
-    use_proxy?: boolean | number,
-}
+import type {DownloadOptions, ProgressCallback} from './interface.js'
 
 /** Fetch a resource */
 const resource_map: Map<string, any> = new Map()
diff --git a/src/common/file/interface.ts b/src/common/file/interface.ts
new file mode 100644
index 0000000..ea49e68
--- /dev/null
+++ b/src/common/file/interface.ts
@@ -0,0 +1,28 @@
+/*
+
+File processing functions
+=========================
+
+Copyright (c) 2024 Dannii Willis
+MIT licenced
+https://github.com/curiousdannii/asyncglk
+
+*/
+
+export type ProgressCallback = (bytes: number) => void
+
+export type TruthyOption = boolean | number
+
+export interface DownloadOptions {
+    /** Domains to access directly: should always have both Access-Control-Allow-Origin and compression headers */
+    direct_domains?: string[],
+    /** Path to resources */
+    lib_path?: string,
+    /** URL of Proxy */
+    proxy_url?: string,
+    /** Whether to load embedded resources in single file mode */
+    single_file?: TruthyOption,
+    /** Use the file proxy; if disabled may mean that some files can't be loaded */
+    // We could just say to exclude proxy_url instead?
+    use_proxy?: boolean | number,
+}
\ No newline at end of file
diff --git a/src/dialog/browser/browser.ts b/src/dialog/browser/browser.ts
index 4d5d953..5c6db11 100644
--- a/src/dialog/browser/browser.ts
+++ b/src/dialog/browser/browser.ts
@@ -12,7 +12,7 @@ https://github.com/curiousdannii/asyncglk
 import {saveAs as filesave_saveAs} from 'file-saver'
 import path from 'path-browserify-esm'
 
-import type {DownloadOptions, ProgressCallback} from '../../common/file.js'
+import type {DownloadOptions, ProgressCallback} from '../../common/file/interface.js'
 import type {DialogDirectories, DialogOptions} from '../common/interface.js'
 import {show_alert} from './common.js'
 import {DownloadProvider, read_uploaded_file} from './download.js'
diff --git a/src/dialog/browser/download.ts b/src/dialog/browser/download.ts
index 41c6cc4..8d86b9d 100644
--- a/src/dialog/browser/download.ts
+++ b/src/dialog/browser/download.ts
@@ -13,10 +13,10 @@ https://github.com/curiousdannii/asyncglk
 
 import {gunzipSync} from 'fflate'
 
-import type {DownloadOptions, ProgressCallback} from '../../common/file.js'
+import type {DownloadOptions, ProgressCallback} from '../../common/file/interface.js'
+import {parse_base64, read_response} from '../../common/file/browser.js'
 import {NullProvider} from './common.js'
 import type {Provider} from './interface.js'
-import {parse_base64, read_response} from '../../common/file.js'
 import {utf8decoder} from '../../common/misc.js'
 
 export class DownloadProvider implements Provider {
diff --git a/src/dialog/browser/interface.ts b/src/dialog/browser/interface.ts
index 68fdc9b..d6f8184 100644
--- a/src/dialog/browser/interface.ts
+++ b/src/dialog/browser/interface.ts
@@ -9,7 +9,7 @@ https://github.com/curiousdannii/asyncglk
 
 */
 
-import type {ProgressCallback} from '../../common/file.js'
+import type {ProgressCallback} from '../../common/file/interface.js'
 import type {AsyncDialog} from '../common/interface.js'
 
 export interface BrowserDialog extends AsyncDialog {
diff --git a/src/glkote/common/glkote.ts b/src/glkote/common/glkote.ts
index 127cc43..23f8e16 100644
--- a/src/glkote/common/glkote.ts
+++ b/src/glkote/common/glkote.ts
@@ -11,7 +11,7 @@ https://github.com/curiousdannii/asyncglk
 
 import {Blorb} from '../../blorb/blorb.js'
 import * as Constants from '../../common/constants.js'
-import type {DownloadOptions}  from '../../common/file.js'
+import type {DownloadOptions}  from '../../common/file/interface.js'
 import * as protocol from '../../common/protocol.js'
 import {filetype_to_extension} from '../../dialog/common/common.js'
 import type {Dialog} from '../../dialog/common/interface.js'
diff --git a/src/glkote/web/schannels.ts b/src/glkote/web/schannels.ts
index 050f2e7..445d0bb 100644
--- a/src/glkote/web/schannels.ts
+++ b/src/glkote/web/schannels.ts
@@ -9,7 +9,7 @@ https://github.com/curiousdannii/asyncglk
 
 */
 
-import {fetch_resource} from '../../common/file.js'
+import {fetch_resource} from '../../common/file/browser.js'
 import * as protocol from '../../common/protocol.js'
 import WebGlkOte from './web.js'
 
diff --git a/src/index-browser.ts b/src/index-browser.ts
index 413cc7e..da07d16 100644
--- a/src/index-browser.ts
+++ b/src/index-browser.ts
@@ -11,7 +11,7 @@ https://github.com/curiousdannii/asyncglk
 
 export * from './index-common.js'
 
-export {fetch_resource} from './common/file.js'
+export {fetch_resource, parse_base64, read_response} from './common/file/browser.js'
 
 export {ProviderBasedBrowserDialog} from './dialog/browser/browser.js'
 
diff --git a/src/index-common.ts b/src/index-common.ts
index 0e2b50d..6c2a211 100644
--- a/src/index-common.ts
+++ b/src/index-common.ts
@@ -14,8 +14,7 @@ export type {BlorbChunk, BlorbDataChunk, ImageInfo, ImageSize, InfoMap, InfoMapR
 export {IFF} from './blorb/iff.js'
 
 export * as constants from './common/constants.js'
-export {parse_base64, read_response} from './common/file.js'
-export type {DownloadOptions, ProgressCallback, TruthyOption} from './common/file.js'
+export type {DownloadOptions, ProgressCallback, TruthyOption} from './common/file/interface.js'
 export {FileView} from './common/misc.js'
 export * as protocol from './common/protocol.js'