Compare PDFs
Compare two PDFs using SHA-256 hashes, page counts/sizes and page-by-page extracted-text differences through ToolLott’s self-hosted PDF runtime. Scanned/image-only visual changes still require visual review.
Use the Compare PDFs
Compare two PDFs using SHA-256 hashes, page counts/sizes and page-by-page extracted-text differences through ToolLott’s self-hosted PDF runtime. Scanned/image-only visual changes still require visual review.
This tool uses ToolLott's self-hosted document runtime. The selected file is sent only to the ToolLott runtime for this operation, is not sent to an external conversion vendor, and temporary processing data is discarded after the response.
Keep the original source file and verify the generated result before relying on it. Modern object/xref-stream PDFs are supported; each tool still has the specific scope and limitations stated in its methodology.
How to use it
Start with the worked settings, choose a local file, inspect the output and keep the original until the generated result has been independently checked.
How the Compare PDFs works
Compare two PDFs using SHA-256 hashes, page counts/sizes and page-by-page extracted-text differences through ToolLott’s self-hosted PDF runtime. Scanned/image-only visual changes still require visual review. The methodology reflects the current self-hosted production runtime and its verified support boundaries.
Calculation breakdown
ToolLott will explain the current inputs and displayed result here.
Process the selected file using the production support boundaries
Compare PDFs validates the selected input and settings, sends the operation to ToolLott’s disclosed self-hosted document runtime where required, and returns the actual artifact/report described here: PDF comparison report: hashes, page structure, changed text pages, similarity and limited text diff. The original file is not overwritten.
| Symbol / input | Meaning | Unit |
|---|---|---|
left | First PDF | user input |
right | Second PDF | user input |
compare | Comparison | user input |
Step-by-step method
- Validate the selected file(s) and all tool-specific page, range, password, layout or output settings before processing.
- Compare two PDFs using SHA-256 hashes, page counts/sizes and page-by-page extracted-text differences through ToolLott’s self-hosted PDF runtime. Scanned/image-only visual changes still require visual review.
- Return the generated artifact or comparison report, surface unsupported/dependency/error states explicitly, and leave the original source file unchanged.
Worked example
Maya, a freelance designer, A contract administrator received two PDFs both labelled “final” and needs to know whether they are byte-identical and whether their page/object counts differ before asking for a visual review.
Example inputs
- Comparison: structural
Calculation / processing
Use the verified QA fixture: Comparison: structural.Run the production Compare PDFs workflow using the documented process the selected file using the production support boundaries.The production runtime QA case reports: PDF comparison: SHA-256 + page structure + extracted text.
This verified result shows what the Compare PDFs produces for the stated scenario. Interpret it together with the inputs, assumptions and limitations instead of treating the displayed summary as context-free advice.
Assumptions
- The source file is readable by the current ToolLott full document runtime and the user is authorised to process or unlock it.
- Tool-specific settings such as page selection, crop, rotation, password, layout, overlay or conversion limits are applied as entered.
Limitations
- No PDF/document conversion can guarantee perfect fidelity for every font, form, signature, embedded object, multimedia feature or damaged file; inspect important output before relying on it.
- Text extraction does not perform OCR unless the OCR tool is used, and scanned/image-only changes are not fully evaluated by text-based comparison.
- Office-to-PDF requires a local LibreOffice runtime and OCR requires Tesseract; if a required capability is missing ToolLott reports it explicitly rather than substituting a lower-fidelity fake result.
- Comparison includes hashes, page dimensions and extracted text; purely visual differences in scanned/image-only content require visual review.
Common questions
What does the Compare PDFs actually calculate or change?
Compare SHA-256 hashes, file size, page structure/dimensions and extracted page text through ToolLott’s self-hosted PDF runtime. It is not a pixel-by-pixel visual diff, so scanned/image-only changes still require visual review.
Does the worked example match the real ToolLott tool?
Yes. The example is linked to the production QA fixture for Build 0272, including its expected summary.
What should I check before relying on the output?
Review the stated assumptions, support boundaries and source references, and independently verify any result used for financial, engineering, legal, archival or production decisions.
Methodology sources
Related ToolLott tools
Open-source components
This tool uses approved open-source runtime components managed in ToolLott's dependency registry.
- pypdf 5.9.0 - BSD-3-Clause licence details
Updating or removing one of these components automatically returns affected tools to Under Development until revalidated.
A realistic way Maya could use this tool
Maya is a freelance designer.
A contract administrator received two PDFs both labelled “final” and needs to know whether they are byte-identical and whether their page/object counts differ before asking for a visual review.
Maya selects both contract copies. ToolLott computes SHA-256 hashes and compares file size, page count/dimensions and extracted page text through the self-hosted PDF runtime, while clearly separating this structural/text check from a pixel-by-pixel visual diff.
The comparison reports 6 pages versus 2 pages and different SHA-256 values, immediately proving the two 'final' files are not byte-identical. Maya now knows a content/visual review is warranted instead of assuming the filenames refer to the same document.
Fictional scenario using realistic example data. For Ready tools, the worked result is tied to the tested example shown in the tool. Replace the figures with your own inputs and independently verify important professional, financial, legal, health or safety decisions.
What this tool is for
Use it to compare two PDFs using SHA-256 hashes, page counts/sizes and page-by-page extracted-text differences through ToolLott’s self-hosted PDF runtime. Scanned/image-only visual changes still require visual review.
It sits within ToolLott’s PDF Tools collection, where you can also merge, split, compress, crop, convert, OCR, protect, unlock, repair, rotate, sign, watermark and edit PDF files.