Duplicate File Detector
Find duplicate files locally using SHA-256 content hashes
Duplicate File Detector — what it does
Select a set of files and the tool hashes each one with SHA-256 and groups files whose content is byte-for-byte identical — regardless of what they are named or where they came from. Content hashing finds the true duplicates that name-based comparison misses: the same photo saved as IMG_1024 and holiday-beach, or the same report downloaded three times.
When this tool helps
- Cleaning a downloads folder where the same attachment was saved repeatedly under numbered names.
- Checking a photo collection for identical shots imported from several devices or backups.
- Verifying that two copies of a delivery are actually identical before deleting one.
How to use it
- Choose the files to scan — select generously, matching is exact.
- Run the duplicate scan.
- Review the duplicate groups the tool reports.
- Delete the redundant copies from your file manager.
Accuracy, limits, and good practice
- Only exact binary duplicates group together; the same photo at two sizes or qualities hashes differently and will not match.
- The tool reports duplicates but never deletes — removal is yours to do, deliberately, in the file manager.
- Hashing reads every byte of every file, so scanning many gigabytes takes real time; batch by folder for large collections.
Frequently asked questions
Can two different files share a hash?
A SHA-256 collision has never been found; for practical purposes a matching hash means identical content.
Do file names affect matching?
Not at all. Only content is hashed, which is precisely why renamed copies are caught.
Which copy should I keep?
Content is identical, so keep whichever name and location serves you best — prefer the one in its organised, final folder.
Related tools on this site
- File Chunk Splitter — Split a file into numbered chunks and download a ZIP
- Monthly Calendar Generator — Create and print a clean monthly office calendar
- Text File Merger — Combine multiple text files in order with a custom separator
Everything above runs inside this page. Duplicate File Detector needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
重複檔案偵測器能做什麼
選取一批檔案，工具會為每個檔案計算 SHA-256 雜湊，並把內容逐位元組完全相同的檔案分成群組——不論檔名為何、來自哪裡。內容雜湊能找出檔名比對抓不到的真重複：同一張照片存成 IMG_1024 與 holiday-beach，或同一份報告下載了三次。
什麼時候用得上
- 清理下載資料夾：同一個附件以編號檔名重複存了好幾份。
- 檢查照片收藏中,從多台裝置或備份匯入的相同照片。
- 刪除前先確認兩份交付檔案內容確實一致。
使用步驟
- 選擇要掃描的檔案——盡量多選，比對是精確的。
- 執行重複掃描。
- 檢視工具列出的重複群組。
- 回到檔案總管刪除多餘的副本。
精確度、限制與實務建議
- 只有二進位完全相同的檔案會成組；同一張照片的不同尺寸或品質，雜湊不同、不會配對。
- 工具只回報、絕不刪除，移除動作由你在檔案總管中自行執行。
- 雜湊要讀完每個檔案的每個位元組，掃數 GB 需要實際時間，大量收藏請分資料夾批次處理。
常見問題
兩個不同檔案會共用同一個雜湊嗎？
SHA-256 至今未發現碰撞；實務上雜湊相同即可視為內容相同。
檔名會影響比對嗎？
完全不會。只比內容，這正是改過名的副本也抓得到的原因。
該留哪一份？
內容完全一樣，留檔名與位置對你最有用的那份即可——優先留在整理好的正式資料夾裡的那份。
本站相關工具
以上步驟全部在這個頁面內完成，重複檔案偵測器 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。