Math & Numbers

Fit zero-order, first-order, and second-order rate equations to concentration-time data. Get reaction order, rate constant k, half-life t½, and R² goodness-of-fit.

Health

Analyze Red Cell Distribution Width (RDW) with MCV to help differentiate anemias. RDW-CV reference ≈ 11.5–14.5%, RDW-SD ≈ 39–46 fL (lab-dependent). Elevated RDW reflects anisocytosis. Classic Bessman patterns: high RDW + low MCV → iron deficiency anemia (IDA), which raises the RDW early — before MCV/Hb fall; normal RDW + low MCV → thalassemia trait (uniform microcytosis). Other patterns: high RDW + high MCV → megaloblastic anemia (B12/folate), MDS, drugs, hemolysis with reticulocytosis, preleukemia, or mixed populations (combined iron + B12 deficiency, post-transfusion); high RDW + normal MCV → early/mixed nutritional deficiency, dimorphic anemia, marrow recovery; normal RDW + normal MCV → anemia of chronic disease is classically normocytic. Interpret with Hb, ferritin, Hb electrophoresis, and clinical context. Based on Bessman 1983 and Teixeira 2014. Not medical advice.

Math & Numbers

Calculate the Rankine passive earth pressure on a smooth vertical wall backfilled with cohesionless soil. K_p = tan²(45°+φ/2). Optional uniform surcharge q. Returns the base pressure p₀, the total force P, and the resultant height. Note: theoretical K_p is an upper bound; designers often apply a reduction factor for wall friction.

PDF Tools

Add a visible typed or image signature block to selected PDF pages and download the signed copy

Security

Estimate real password strength with Shannon entropy, zxcvbn pattern matching (l33t, dictionary, sequences, repeats) and brute-force crack-time across attack scenarios (offline fast/slow hash, online). The password is evaluated locally and never sent anywhere.

Document Tools

Convert PDF documents to a self-declared PDF/A archival profile with zero external dependencies

Document Tools

Pre-validate PDF documents for PDF/A archival compliance

Document Tools

Audit PDF documents for accessibility features like tagging, language and PDF/UA metadata

Document Tools

Compare two PDF documents page by page and highlight text differences

PDF Tools

Extract existing annotations (highlights, comments, stamps, links, markup) from a PDF into JSON

PDF Tools

Remove visual noise from scanned PDF pages — salt-and-pepper speckle, random grain, and faint background haze — using real image-processing algorithms. Text pages are preserved as searchable vector content.

PDF Tools

Automatically detect and correct skewed (tilted) PDF pages. Preserves text pages as searchable vector content and only rasterizes image pages (e.g. scans).