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Compare metadata in FLUX image exports

See how FLUX downloads differ across local ComfyUI workflows and hosted exports, and which embedded records you can inspect.

FLUX image metadata depends on how you got the file. A PNG saved by ComfyUI can carry the text and settings used in a generation, along with a graph you can reopen. A Black Forest Labs API job can return an expanded prompt in its JSON response and deliver a signed image as a separate download. If you want to recover a prompt or check an image’s provenance, start by identifying the export path.

Identify the FLUX model and the tool that saved the file

FLUX is Black Forest Labs’ model family. Its documentation covers FLUX 3 Image and FLUX 3 Image Klein, the FLUX.2 family, and earlier endpoints such as FLUX.1 Kontext. The model name describes what ran. The application or service that saved your copy determines which records it wrote. For a local workflow, note the model file, application version and save node. For a hosted job, note the service, endpoint and download method. Black Forest Labs model documentation

Keep the first saved copy. If you also have an edited file or a platform download, inspect both and compare the results. A missing entry in the later copy can tell you what changed between the two files.

Local ComfyUI PNG exports

Save Image settings

With metadata enabled, ComfyUI’s built-in Save Image node can write the executed graph under the PNG text key prompt. It can also write additional records supplied by the application, including a workflow entry when one is supplied. Starting ComfyUI with --disable-metadata skips those writes in the stock node. Custom save nodes and other exporters can behave differently. ComfyUI SaveImage implementation

What the workflow record contains

In the ComfyUI project’s published FLUX.1 [dev] example, the 1024 × 1024 PNG contains two text entries. The prompt JSON identifies flux1-dev.safetensors, includes a text-encoding node and records settings across several nodes. The seed is in RandomNoise, the 20 steps and scheduler are in BasicScheduler, and the guidance value of 3.5 is in FluxGuidance. The separate workflow JSON stores the canvas graph and its node connections. Those are observations from this example. Other workflows can organize inputs differently. ComfyUI FLUX.1 [dev] example PNG

If you plan to revisit a local generation, save the workflow JSON separately. Reopening a graph gives you its configuration. Running it again also requires the models, nodes and any input assets it references. ComfyUI FLUX examples

The published PNG was inspected for its embedded records. No new local FLUX generation, workflow reload or cleanup test was performed on this sample. Fresh BFL API or Playground downloads were not independently tested.

Hosted FLUX API files and responses

For BFL’s FLUX 3 Image endpoint, submit a job and poll the returned polling_url. When the job is ready, download the image from the temporary URL in result.sample. BFL’s guide saves that download as PNG. The JSON also supplies result.prompt, which BFL describes as the expanded prompt used for generation. Save the request if you need the wording you originally submitted, and keep the relevant response fields alongside the image if you need the expanded version. Finding a prompt in the response only establishes that the API returned it there. Black Forest Labs FLUX 3 Image guide

BFL also offers FLUX through its browser Playground. Start with the direct download and check any available project or generation history for settings that are missing from the file. For a third-party FLUX service, use that provider’s documentation and inspect its own download. A provider can expose generation details on a page or in an API response even when its downloadable image has fewer records. Black Forest Labs Playground and API overview

What changes across output formats

FLUX.2 [pro] exposes an output_format option for JPEG, PNG and WebP, with JPEG as the documented default. It also accepts an optional seed. These are request options for that endpoint. Choosing PNG gives you a format that can contain text chunks, while the exporter determines whether it writes any prompt or workflow keys. JPEG and WebP use different metadata structures, so search the categories the file actually contains. A converter, image editor or social upload may preserve, omit or rewrite records when making another copy. FLUX.2 [pro] API reference · W3C PNG specification · BFL guidance on preserving credentials

Does FLUX add Content Credentials?

Black Forest Labs says it attaches signed C2PA Content Credentials to final images from its API and Developer Playground, as well as hosted integrations where it controls the output pipeline. Its credentials can identify the model and record that AI was used. BFL says the credential excludes text prompts. Its signing infrastructure covers its own pipelines, so check the file from a self-hosted or third-party deployment for whatever provenance that exporter supplies. Black Forest Labs C2PA documentation

Review the signature and file-binding results separately from any signer trust assessment. An edited copy can lose its embedded record or fail a binding check. A file with no detected credential can still be AI-generated. C2PA Content Credentials explainer

How to inspect FLUX image metadata

Open AiMetaOff’s Metadata Viewer and choose the original output file. The viewer reads the file locally in your browser.
Open Metadata & verification. For a ComfyUI PNG, check Text for keys such as prompt and workflow. Review XMP and EXIF when present. For JPEG, the viewer can also flag supported IPTC data by its APP13 container.
For a hosted download, review the C2PA checks separately. The viewer can read supported embedded manifests and report available offline verification results. For the prompt or settings, compare the report with the saved API request, response or app history.

Inspect a FLUX output file

Remove supported embedded generation records

Keep the original and any workflow JSON you need. In Cleanup scope, select Text for supported PNG workflow entries or XMP if the record you want to remove is in a supported XMP packet. The tool removes whole selected categories, so check for captions and other entries you want to keep before selecting Clean selected. EXIF, JPEG IPTC blocks and supported embedded C2PA containers have separate cleanup categories. Text and XMP cleanup alone gives no assurance that a credential remains valid. See supported text cleanup.

Cleanup applies to the copy you download. A prompt saved in API history, a workflow sidecar, a watermark encoded in the image, and a label assigned by another service are outside that file-metadata operation.

Verify the downloaded copy

Choose Download new copy and open that file again in Inspect File. Compare Input, Output and Retained in the cleanup report. Confirm that the entries you targeted are absent from the new file’s inspection.
Compare the original and download at the same dimensions. Check transparency and color where they matter. For a byte-level check on a supported PNG, compare the ordered IDAT payloads or compare decoded pixels. A full-file hash will change when you remove a chunk.
If you need to preserve verifiable provenance, check the downloaded copy’s credential separately and keep the signed original. For the full comparison procedure, see how to verify metadata removal.

FAQ

Can I find the original FLUX prompt in a downloaded image?

Sometimes. In a ComfyUI PNG, look inside the saved graph for the text or conditioning input used by the generation. The prompt key itself usually holds JSON. For the documented FLUX 3 Image API workflow, look in the saved request for your original text and in result.prompt for the expanded text. If all you have is an image without a usable record, its appearance cannot recover the exact original wording.

Does every FLUX PNG contain a ComfyUI workflow?

No. A PNG can contain a workflow only if a tool writes it. A hosted PNG, a ComfyUI export with metadata disabled, or a copy created by an editor can lack that record.

Can AiMetaOff tell which FLUX model made an image?

It can show model information when a supported record contains it. Its report describes records found in the file and any available credential checks. It cannot identify the model from the pixels.

Does missing C2PA prove that a FLUX image was made by a person?

No. A local exporter may never have attached a credential, and a later copy can lose one. Inspect the direct export when available and treat a missing record as a finding about the file you checked. C2PA Content Credentials explainer