Missing numbers
Find a gap such as 0001, 0002, 0004.
Find missing or repeated file numbers instantly.
Drop related files or a folder. The checker compares names, finds gaps and duplicates, and shows the result in plain language.
Selected files are not uploaded0 bytes of file contents readRuns in your browser
Drop files or a folder
Select at least two related files to compare their numbers.
Ready for files.
Private by design: only file names and relative folder paths are checked. File contents are never opened or uploaded.
Settings Recommended defaults work for most folders
Checking file names…
Nothing is being uploaded.
Check complete
Results
What needs your attention
More options
Technical details Detected sequences and rename suggestions
| Detected sequence | Folder | Files | Number used | Range | Step | Confidence |
|---|
What this checker can find
Use it for image sequences, render frames, scanned pages, product photos, webtoon pages, and any folder that uses numbered file names.
Repeated numbers
Find two files that both use the same sequence number.
Naming differences
Spot zero-padding, extension, and file-name pattern differences.
Frequently asked questions
Privacy and browser behavior, explained simply.
Are my files uploaded?
No. The checker works with names and relative paths in your browser. It does not read file contents.
Why should I select at least two files?
A single file does not provide enough information to identify a sequence, gap, or duplicate.
Can it rename my files?
No. It can show safe rename suggestions, but it never changes files.
Check the sequence, then review the flagged files before renaming anything
SeqName is designed to narrow a large folder down to the filenames that deserve attention. It never renames files automatically, because a missing number can be intentional and a repeated number can represent a legitimate sidecar file or alternate format.
1. Start with related files
Select files that belong to the same export, scan, render, photo set, or numbered document series. Mixing unrelated naming conventions makes the intended sequence harder to infer.
2. Review confidence and pattern
When the number position or spacing is ambiguous, the checker marks the result for review instead of declaring a missing value with false certainty.
3. Rename outside the checker
Use the report as a checklist. Keep a backup and perform the actual rename in a file manager or another tool after confirming the intended order.
Examples of what the checker distinguishes
frame_0001.png, frame_0002.png, and frame_0004.png provide strong evidence for a one-step sequence with 0003 missing. A sparse set such as take_10, take_20, and take_40 is different: the intended interval may be 10, or the numbers may be labels rather than a complete sequence. SeqName's analysis includes confidence and review states so that ambiguous spacing is not silently converted into a definite error.
What the browser receives
When you select files, the checker uses their names and relative folder paths to build the sequence model. It does not open or parse the selected file contents. Analysis results remain in page memory unless you choose to copy or download a report. The page stores a theme preference separately in browser storage.
Limitations
- A filename can contain a date, version, resolution, and sequence number at the same time. The checker uses heuristics and can choose the wrong numeric part; low-confidence results are marked for review.
- A missing number is not necessarily a missing file. Some workflows intentionally skip numbers.
- Different extensions can be separate deliverables or sidecars rather than duplicates. Use the settings that match your workflow.
- The checker cannot know the creative or business meaning of a filename. Confirm flagged items against the source project before renaming or deleting anything.
Related guides
Use How to Find Missing Files and Duplicate Numbers in a Filename Sequence for a complete review workflow, including mixed patterns, padding, sidecars, and safe completion checks. If a batch rename is required afterward, keep the original folder or a backup and preview the proposed names first; Tweaknook's bulk file renaming guide covers a separate Python workflow.