A custom Codex pet is more than a small character image. It is an animated companion packaged in the format Codex expects. This guide follows the complete path from choosing one source photo to installing a working pet with nine motion states.
What is a Codex pet?
A Codex pet is a small animated companion that appears inside Codex while you work. It can wait, run, wave, jump, react to failure, and take part in other moments across the coding workflow.
A custom kit normally includes pet.json, which describes the pet, and spritesheet.webp, which stores its animation frames. Codex reads these files together and displays the correct motion for each state.
Codex Pet Kit is an independent compatibility tool. It is not an official OpenAI product, but it packages generated pets for the custom pet format used by Codex.
1. Choose a clear source image
Start with one obvious subject: a person, pet, mascot, logo, or object. A front or near-front view with even lighting gives the generator enough information to preserve the silhouette and important details.
Choose two or three identity cues that matter most. In this example, the purple heart clips, white sweater, long hair, and peace sign make the final pet immediately recognizable.
Avoid crowded group photos, severe blur, heavy obstruction, extreme camera angles, and tiny printed text. These details are difficult to keep consistent across dozens of frames.
2. Choose the Codex pet style
Pixel Pet turns the subject into a crisp game-like sprite with a stronger pixel-art silhouette. It works well for animals, mascots, logos, and subjects that remain recognizable after bold simplification.
Chibi Pet uses a cute oversized head, compact complete body, rounded 2D shading, and expressive motion. It works well for people, pets, and illustrated characters that benefit from a more playful look.
Founder Pet uses softer proportions and retains more information from clothing, hair, and accessories. It is usually the better choice for portraits, creators, founders, and personal gifts.
Choose the style based on what must remain recognizable, not only on which preview looks more detailed. Pixel Pet, Chibi Pet, and Founder Pet all produce the same installable kit structure.
3. Generate all nine animation states
Upload the source image, choose a style, enter a valid generation code, and start generation. A complete run usually takes about 10 to 15 minutes, depending on model response time and image complexity.
The workflow builds 72 frames across nine states: idle, running right, running left, waving, jumping, failed, waiting, working, and review.
These are separate motion sequences, not copies of one still image. Limbs, expression, direction, and pose need to change while the character identity stays consistent.
4. Review and download the complete pet kit
When generation finishes, check the transparent preview and motion contact sheet. Look for a recognizable face or silhouette, consistent clothing and colors, readable movement, and clean transparent edges.
Download the ZIP before leaving the result page. The package includes pet.json, spritesheet.webp, preview.png, contact-sheet.png, and README.md.
Keep the extracted folder intact. Renaming or separating pet.json and spritesheet.webp can prevent Codex from finding the pet correctly.
- pet.json defines the pet identity and spritesheet path
- spritesheet.webp contains the complete animation atlas
- preview.png shows the character on a transparent background
- contact-sheet.png provides a visual motion check
- README.md contains installation notes
5. Install the custom pet in Codex
Unzip the downloaded file. In Codex Settings, open Pets and use Open folder to reveal the correct custom pets directory instead of trying to locate the hidden folder manually.
Move the whole extracted pet folder into that directory. pet.json and spritesheet.webp should sit directly inside the pet folder, without an extra nested folder between them and the custom pets directory.
Return to Codex, refresh the custom pets list, and select the new pet. If it does not appear, check the folder nesting and file names first.
Common mistakes and realistic expectations
AI-generated animation may contain small differences in hands, accessories, edges, or fine clothing details. A strong result should remain recognizable and usable, but it may not reproduce every source detail perfectly.
If a model safety check blocks the source or generation fails technically, the generation code is restored according to the service rules. Try a clearer and less sensitive source image before generating again.
For the best result, treat image choice, style choice, motion review, and folder structure as parts of one workflow rather than judging only the first preview frame.
- Use one clear subject and good lighting
- Keep important visual details large and visible
- Review movement across all nine states
- Download the ZIP before closing the result page
- Move the complete folder without renaming required files
Choose one clear image, select the style that preserves the right identity cues, generate and review all nine states, download the complete ZIP, then place the intact pet folder in the custom pets directory opened by Codex.