Drop Capability Probe

Finds out what this browser and this network will actually let us do, so the file bridge gets designed around real constraints instead of assumed ones. Nothing is stored and nothing leaves this page except the report you copy out yourself.

1 · Automatic checks

Run on load. No interaction needed.

Only about 1 MB is uploaded on load. The larger rungs are opt-in, since a sudden 32 MB POST on a monitored network is worth doing on purpose rather than by surprise.

2 · Can this browser read a local file?

The three ways a browser can obtain local bytes. If all three fail, binaries can only leave this machine as text.

File picker

Opens a normal file dialog. Pick any small file - it is read locally and never uploaded.

Drag and drop

Drag a file onto this area

Clipboard file read

Copy a file in Explorer or Finder first, then press the button.

3 · How much text survives a paste?

The text-out path is only as wide as the largest paste that arrives intact. DLP tooling often truncates large pastes silently, so every payload carries numbered lines and an end sentinel - if it gets cut, we can say exactly where.

Payload to copy

Copied automatically. If that is blocked, click inside and press Ctrl+A then Ctrl+C.

Paste it back here

4 · Can this browser save a file?

The in-direction depends entirely on this. Confirm each one actually lands in your Downloads folder at the stated size.

5 · Can you run one local command?

This is the fork in the road. If a shell runs, binaries can leave this machine properly via a small uploader script and none of the base64 paste awkwardness is needed. If not, binaries cannot leave through a browser at all.

Step 1 - run whichever of these works

PowerShell   [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes("PROBE"))
cmd + certutil   echo PROBE> p.txt && certutil -encode p.txt p.b64 && type p.b64
macOS / Linux    printf PROBE | base64

Step 2 - paste what it printed

The expected answer is shown once you generate the challenge, so a copied answer from elsewhere will not pass.

Report

Getting this off the machine is itself the text-out test. If you can copy it into an email or a chat, mode 2 works.