Bring supporting documents within the UPSC portal's upload limits, compressed on your own device.
It varies by document type and by application cycle, and the portal states it on the upload screen. Use that figure rather than one quoted on a third-party site.
The portal specifies acceptable formats for each field. A clear scan or photograph saved in the required format is normally acceptable, but check the instruction text for the field you are filling.
Not if you compress to the stated limit rather than the smallest possible size. The tool picks the best quality that fits your target.
No. Compression runs in your browser using your own device. The file never leaves it, which matters for identity documents, marksheets and financial records.
None of the three. The tool is free, adds nothing to your document and does not require an account.
UPSC's online application asks for a photograph, a signature and — at the Detailed Application Form stage — scanned supporting documents including education certificates, category certificates and age proof. The document uploads are where people usually run into size limits, because scanned certificates are large.
UPSC states the accepted formats and maximum sizes on the upload screen and in the instructions accompanying each stage. These differ by document type and change between cycles. Enter the figure the portal gives you into the target box below.
A verifying officer has to read what you upload. Compress to the limit you were given, not to the smallest number you can achieve — an over-compressed certificate that cannot be read is worse than one that is merely large.
Education and category certificates carry personal data. Nothing here is uploaded: the compression happens in your browser, so the file never reaches a server.
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Also useful: UPSC photo and signature size · Compress PDF to 200KB · Compress PDF to 300KB
Related: compress PDF (any size) · enter your own target