A privilege log lists every document you are keeping back, enough to identify it, and why it is privileged, without describing the privileged thing itself. This builds one and checks it: a control number used twice, a date that is not a date, a claim with no basis, a redaction with no document number, a legal advice claim with no lawyer on it, a description that repeats what the document says. A defective log is how a privilege gets waived.
It checks what a spreadsheet cannot. A control number used twice, a date that is not a date, a communication with no recipient, a claim with no basis, a redaction with no document number, and a legal advice claim where nobody from your list of lawyers appears on the document.
It watches the description. A log entry identifies a document; it does not repeat what the document says. Phrases like "advising that" and "stating that" are flagged, because that is how a description becomes a partial disclosure.
Hashes tie the log to the documents. Attach a file to an entry and its SHA-256 is recorded. The file is read to hash it, never kept and never uploaded, so months later you can show the document logged is the document produced.
It does not know your rules. The bases offered cover the common English and American claims. What a log must contain, and how much detail it must give, is set by your court's rules and your jurisdiction. This gives you a clean, complete, checkable log; you check it against the rules that apply.
Nothing leaves this tab. The log is kept in this browser and, with a folder connected, in it. Export the JSON as your backup.
Usually: a number, the date, the type of document, who wrote it, who received it, who was copied, a description that identifies it without disclosing it, and the basis of the claim. Some courts require more, some allow categorical logging for whole classes of document. Check the rule that applies before you file.
Enough for the other side to test the claim and no more. "Email from in-house counsel to the finance director seeking legal advice on the draft supply agreement" identifies it; "email advising that the clause was unenforceable" gives away the advice.
A withheld document is not produced at all. A redacted one is produced with parts blacked out, so it has a Bates or document number the other side can point at, which is why the log asks for one.
Yes: export the JSON and load it back. The log is also kept in this browser between visits, and in your folder if you have connected one.