Private file preflight

Check My File

Understand the file before you change it. Check the real format, useful properties, likely compatibility, and the safest next step without uploading or modifying the file.

Checked on your device No upload Original stays unchanged

Choose any common file

Images, PDFs, audio, video, text, ZIP archives, and modern Office files are checked when the browser can read them.

or drop one file here

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No personal file handy?

Samples are generated in this browser and are never downloaded to your device.

Will this upload?

Copy the rules from the website or form you plan to use. Leave any rule blank when it does not apply. Everything stays in this tab.

Choose a destination to load its documented checks. Every preset links to its official source, shows when it was reviewed, and separates requirements from recommendations.

Something else

You changed the sourced values. The official links describe the original preset; the checker now uses your edited values as custom rules.

{{ rule.kind }} {{ rule.label }} checked here read and check manually
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Official source: {{ source.publisher }}

Limits these checks do not cover

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No acceptance guarantee. {{ selectedDestinationProfile.preset.acceptanceDisclaimer }}

Or start with a generic rule example

These examples are not destination requirements. They replace the current rules and can be changed.

File basics

Size uses decimal upload limits: 1 MB is exactly 1,000,000 bytes. Formats are checked against the detected contents, not just the file name.

Maximum file size

Leave blank for no size limit. {{ requirementFieldError('maxSize') }}

Allowed formats Separate extensions with commas or spaces. {{ requirementFieldError('allowedFormats') }}

Pixel dimensions

These rules apply to images and videos. Enter only the minimums or maximums the upload form gives you.

{{ field.label }} (px) {{ requirementFieldError(field.key) }}

Aspect ratio

Enter both sides, such as 16 and 9. Tolerance allows small crops or rounding differences.

Required ratio

Tolerance (%) 0% means an exact ratio. Maximum 50%. {{ requirementFieldError('aspectTolerance') }}

Image behavior

Use these only when the destination explicitly rejects animation or transparent pixels.

Must be a still imageFails when multiple animation frames are detected. Must not contain transparencyChecks decoded pixels when the browser can safely sample them.

PDF rules

Custom PDF rules fail for non-PDF files. A sourced destination preset can mark a PDF-only page check as not applicable to another accepted format. Searchable text is sampled from up to five pages.

Maximum number of pages Leave blank when page count does not matter. {{ requirementFieldError('maxPdfPages') }}

Must contain selectable textChecks text on up to the first five PDF pages. Must open without a passwordFails when password protection is detected.

Fix the highlighted rule fields before relying on the upload result.

Read-only and local. The checker reads selected bytes and properties in this tab. It does not upload, rename, convert, repair, or save your file. A format-specific code library may download for deeper checks.

A plain-language report appears here

We will separate confirmed facts from likely clues, compare every upload rule you entered, and explain any recommendation before you open another tool.

Code: {{ failure.code }}

The diagnostic contains an error code, browser, detected format if available, and a size range. It excludes the file name and contents.

Detected from file contents

What we could verify

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Sample of archive entries

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Will this upload?

Fix the highlighted upload rules The file result is paused until every entered rule is valid.

No upload rules are active. Add the limits from the form you plan to use, and this result will update without reading the file again.

Checks and cautions

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Useful next steps

{{ tool.label }} {{ tool.summary }} Before you use it: {{ tool.disclosure }}

No converter is recommended from this evidence. That is safer than guessing. Try opening the file in its usual app, or tell us which format you need help with.

Did this file check help?

JPEGConvert adds your Yes/No answer, optional reason, and detected format to the site’s analytics event. Standard analytics context may also apply. We do not add your file name or contents.

What this check can—and cannot—tell you

A useful preflight should make its limits as clear as its findings.

Strong evidence

Recognized file signatures and container structures
Exact byte size and extension comparison
Properties decoded by this browser, such as dimensions or duration
Text found on the sampled PDF pages

Needs context

Whether a particular website will accept the file
Whether every PDF page is searchable when only five are sampled
Whether an uncommon codec works in another device or app
Whether a damaged file can be repaired safely

How to check a file before using it

Choose a file

Select one file or use a generated sample. The original stays on your device.

Read the evidence

Compare the real format, extension, useful properties, and every upload rule you entered.

Choose a safe next step

Open a recommended tool only after reviewing what it changes or removes.

Content-aware format check

Compare recognizable file signatures, the browser type, and the filename extension instead of trusting the name alone.

Useful file details

See the properties the browser can verify, such as dimensions, pages, duration, encryption, or searchable PDF text.

Capability-backed next steps

Recommendations come from the same tool capability contract used by converter pages and tests.

Requirement checks

Check common goals such as a size limit, a searchable PDF, or a broadly supported web image.

Private inspection

Analysis runs in your browser. The file is not uploaded and its contents are not recorded.

Read-only by design

The checker does not repair, convert, rename, or otherwise change the selected file.

Frequently Asked Questions

No. Inspection runs in your browser and is read-only. The file is not uploaded, renamed, converted, or saved by this tool.

A file can be renamed without converting its contents. The checker compares recognizable bytes with the extension and browser-provided type to flag likely mismatches.

It reports basic details for any selected file and can inspect additional properties for common images, PDFs, audio, and video when the browser supports that format.

It checks sampled pages for usable text. Little or no extracted text can indicate scanned pages, but mixed documents and decorative text still require a visual check.

No. It explains what could be read and recommends a compatible tool or recovery step. Keep the original file until you have verified any converted result.

No browser tool can guarantee every codec, damaged file, or unusually large document. Recommendations reflect verified tool capabilities and clearly state practical browser limits.

Need a hand with your file?

JPEGConvert.com keeps the workflow simple: upload, convert, and download. For the best results, start with the highest-quality source file you have.

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Check My File

Choose any common file

Where will you use this file?

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A plain-language report appears here

{{ failure.title }}

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What we could verify

Will this upload?

Useful fixes for this result

{{ plan.title }}

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Checks and cautions

Useful next steps

Did this file check help?

What this check can—and cannot—tell you

Strong evidence

Needs context

How to check a file before using it

Choose a file

Read the evidence

Choose a safe next step

Content-aware format check

Useful file details

Capability-backed next steps

Requirement checks

Private inspection

Read-only by design

Frequently Asked Questions

Need a hand with your file?

Check My File

Choose any common file

Where will you use this file?

{{ selectedDestinationProfile.preset.label }}

A plain-language report appears here

{{ failure.title }}

What we could verify

Will this upload?

Useful fixes for this result

{{ plan.title }}

{{ item.title }}

Checks and cautions

Useful next steps

Did this file check help?

What this check can—and cannot—tell you

Strong evidence

Needs context

How to check a file before using it

Choose a file

Read the evidence

Choose a safe next step

Content-aware format check

Useful file details

Capability-backed next steps

Requirement checks

Private inspection

Read-only by design

Frequently Asked Questions

Does Check My File upload or change the file?

Why can the real format differ from the extension?

What can the checker inspect?

Can it tell whether a PDF is scanned?

Does it repair damaged files?

Are recommendations guaranteed to work with every file?

Need a hand with your file?