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Practical guides for comparing, reviewing and working with documents — written for people who deal with contracts, official documents and PDFs every day.

Document integrityJuly 9, 2026 7 min

SHA-256 hash — what it is and how to prove a file has not been altered

Understand what a SHA-256 hash is (the "fingerprint" of a file), how to calculate the hash of a PDF on Windows, Mac or directly in your browser, and how to use this technique to prove a document was never modified.

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Document comparisonJuly 9, 2026 7 min

Document comparison done right — the complete workflow to check, prove and submit

The professional step-by-step for comparing PDF documents from start to finish — organizing the files, running the automatic comparison with difference highlighting, generating a report with SHA-256 hashes and preparing the final document for systems with size limits.

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Document integrityJuly 9, 2026 8 min

Document cryptography — hash, digital signature and timestamp (what each one proves)

A complete guide to cryptography applied to documents, for non-technical readers — the difference between a SHA-256 hash, a digital signature and a trusted timestamp, what each mechanism proves, and the mistakes that silently invalidate a digital signature.

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Document comparisonJuly 8, 2026 4 min

How to compare two versions of a contract in PDF (without installing anything)

A practical guide to finding every change between two versions of a PDF contract — modified clauses, altered deadlines and added passages — right in your browser, without sending your files to the internet.

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Tenders and procurementJuly 8, 2026 3 min

"Amended tender documents: how to find exactly what changed"

An amendment to the tender, RFP or official notice just came out? Learn how to compare the original version with the amended one and find every change — deadlines, requirements and annexes — in minutes, without rereading the whole document.

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Privacy and securityJuly 8, 2026 4 min

"Comparing PDFs online without uploading your files: why it matters"

Most online PDF tools send your documents to third-party servers. Understand the risks — professional secrecy, GDPR, confidentiality — and how 100% local processing in the browser works.

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