Canonical: https://rom-weaver.com/docs/test-roms

# ROM tester online: play and test a patched ROM

Use rom-weaver's ROM tester online to test a patched ROM before downloading it. Open [Test](<https://rom-weaver.com/test-rom>) to play local games through EmulatorJS. Play NES, SNES, Game Boy, GBA, Nintendo 64, Nintendo DS, and PlayStation games.

Your ROM stays on your device; no upload or account is required.

To verify the exact file a patch requires, use [Checksum](<https://rom-weaver.com/docs/checksum-roms-browser.md>) to compare its hash with the author's expected value, or [Identify](<https://rom-weaver.com/docs/identify-roms-browser.md>) to look up a known game, region, and revision. Playing a game successfully does not verify its checksum.

If you need a practice file, open [guided Test](<https://rom-weaver.com/test-rom?guide=test>). It loads a tiny homebrew NES ROM from this project.

<a id="play-and-test-a-rom-in-your-browser"></a>

<!-- START doctoc -->
## Table of contents

- [Check platform support](<#check-platform-support>)
- [Load a ROM](<#load-a-rom>)
- [Test an Apply result](<#test-an-apply-result>)
- [Switch games or stop](<#switch-games-or-stop>)
- [Use saves and fullscreen](<#use-saves-and-fullscreen>)
- [Export and restore a save](<#export-and-restore-a-save>)
- [Disable save storage](<#disable-save-storage>)
- [Fix a game that does not start](<#fix-a-game-that-does-not-start>)

<!-- END doctoc -->

## Check platform support

1. Check [browser emulator support](<https://rom-weaver.com/docs/supported-formats.md#browser-emulator-support>) for your game's platform and the bundled core limitations.
2. For GameCube, Wii, Nintendo 3DS, Dreamcast, or PlayStation 2 games, use an emulator for that platform. Converting, patching, or identifying a ROM in rom-weaver does not mean the browser player supports it.
3. Keep the original ROM and use a copy when testing a patch.

## Load a ROM

1. Open [Test](<https://rom-weaver.com/test-rom>).
2. Drop a ROM onto **0x01 Load a game**, or select that area to choose a file.
3. If the player shows **START GAME**, select it. Touch devices can require this tap before playback starts.
4. Use the controls inside the emulator player.

You can also add a ZIP or 7z archive. rom-weaver shows the extraction progress, then opens a supported ROM from the archive.

A CHD that rom-weaver identifies as Sony PlayStation or Sega Mega Drive or Genesis opens without extraction. A CHD identified as Sega CD or Mega-CD has no bundled core and does not play. The emulator core reads the CHD directly, so a multi-track CD plays as one file. Add the `.chd` file itself, not an archive that contains it. A CHD for any other platform, including Saturn, is extracted first.

[Browser emulator support](<https://rom-weaver.com/docs/supported-formats.md#browser-emulator-support>) lists the platforms with bundled cores.

<figure class="docs-screenshot">
  <picture data-docs-screenshot-theme="light">
    <source media="(max-width: 520px)" type="image/avif" srcset="../screenshots/test-player-mobile-light.avif" width="1170" height="2314">
    <source type="image/avif" srcset="../screenshots/test-player-desktop-light.avif" width="1770" height="1489">
    <source media="(max-width: 520px)" type="image/webp" srcset="../screenshots/test-player-mobile-light.webp" width="1170" height="2314">
    <img src="../screenshots/test-player-desktop-light.webp" alt="Test player showing the HELLO WORLD homebrew ROM and its SHA-1 fingerprint in the light theme" width="1770" height="1489">
  </picture>
  <picture data-docs-screenshot-theme="dark">
    <source media="(max-width: 520px)" type="image/avif" srcset="../screenshots/test-player-mobile-dark.avif" width="1170" height="2314">
    <source type="image/avif" srcset="../screenshots/test-player-desktop-dark.avif" width="1770" height="1489">
    <source media="(max-width: 520px)" type="image/webp" srcset="../screenshots/test-player-mobile-dark.webp" width="1170" height="2314">
    <img src="../screenshots/test-player-desktop-dark.webp" alt="Test player showing the HELLO WORLD homebrew ROM and its SHA-1 fingerprint in the dark theme" width="1770" height="1489">
  </picture>
  <figcaption>The supplied homebrew ROM runs in Test. The fingerprint identifies the file used for stored saves.</figcaption>
</figure>

## Test an Apply result

To test a patched ROM online, send the Apply result directly to the browser player:

1. Load your ROM and patches on the [Apply Patches page](<https://rom-weaver.com/apply-patches>).
2. Set **Open Test after patching** under **Options**, then apply the patches. If the option warns that the platform cannot be tested, use another emulator or the target hardware.
3. Select **Open in the Test tab** after Apply finishes.
4. Play far enough to exercise the patched content.
5. Return to Apply and download the result if you have not downloaded it.

The **Open Test after patching** option can open Test automatically or hide the Test button. Apply skips automatic testing for unsupported platforms. Its disabled Test button names the unsupported platform.

Use **Download after patching** to choose whether Apply downloads the result automatically.

An emulator test does not prove that every part of a patch works. Keep the clean original and test important paths on the target hardware when possible.

## Switch games or stop

Select **Choose another ROM** to replace the current game. Select **Stop** to unload the game and return to the Test start screen.

The emulator pauses when you leave the Test page or hide the browser tab. It resumes when you return.

## Use saves and fullscreen

Use the emulator menu to create a save state or save the game's SRAM. rom-weaver stores the save bytes in this browser.

Each save uses the ROM's SHA-1 checksum as its identity. The record also stores the file name as a display name. Thus, the same ROM finds its save after you rename the file.

The panel above EmulatorJS shows the current file name and complete SHA-1. Storage shows the same value as a ROM fingerprint. You only need these values when you troubleshoot a save mismatch.

Use the fullscreen button above the player to enter or leave fullscreen. On iPhone and iPad, the button uses a full-viewport player because Safari does not offer fullscreen for this type of content.

## Export and restore a save

Export a save before you clear browser data or move to another browser.

1. Load the ROM on the [Test page](<https://rom-weaver.com/test-rom>).
2. Create a save state or save the game's SRAM from the emulator menu.
3. Open **Settings**, then select **Saves & storage**.
4. Find the ROM under **Emulator saves**.
5. Select **Export** and keep the downloaded ZIP file.

Restore the save in a browser that has the same ROM:

1. Open **Settings**, then select **Saves & storage**.
2. Select **Import save**.
3. Choose the exported rom-weaver ZIP file.
4. Confirm that the ROM name and SHA-1 appear under **Emulator saves**.
5. Load the same ROM on the Test page.
6. Select **Load State** from the emulator menu.

**Saves & storage** also accepts the older uncompressed JSON export.

To import a raw SRAM or save-state file:

1. Open **Settings**, then select **Saves & storage**.
2. Select **Import save**.
3. Choose the file exported by the emulator settings.
4. Select **SRAM** or **Save state**.
5. Enter the ROM's 40-character SHA-1.

The import merges with any other save part for the same SHA-1. You can select **Delete** before the import if you want to test the complete restore process.

## Disable save storage

1. Open **Settings**.
2. Clear **Store emulator saves on this device**.
3. Select **Save**.

New save states and SRAM are not stored while this setting is off. Existing saves remain in **Saves & storage** until you delete them.

Use the **Delete** action in **Saves & storage** to remove one game. Use your browser's site-data controls to remove all rom-weaver data.

## Fix a game that does not start

- **No emulator core for this system:** check [browser emulator support](<https://rom-weaver.com/docs/supported-formats.md#browser-emulator-support>).
- **A Famicom Disk System `.fds` game shows a BIOS message:** these games need the FDS BIOS, and the Test page cannot load one yet, so the emulator does not start. The same applies to an `.fds` file inside a ZIP or 7z archive and to an Apply result. [Issue #1223](<https://github.com/rom-weaver/rom-weaver/issues/1223>) tracks BIOS support.
- **WebGL 2 is required:** enable hardware acceleration or use a browser that supports WebGL 2.
- **An archive does not load:** extract it yourself, then add the ROM file.
- **A save does not appear:** load the same ROM bytes. rom-weaver uses the ROM's SHA-1 checksum to find its saves.
- **An imported save does not load:** confirm that its SHA-1 matches the ROM shown in Storage.
- **The player has no sound on iPhone or iPad:** start the game inside the player. Safari requires that direct tap before it enables audio.

The emulator and its selected cores download from rom-weaver's own origin. Load a game for each system you plan to use while online, so its emulator core is cached before you go offline.