Here are some free, open-source examples by Presidio Vantage.
All assets here are provided under the MIT License.

Never follow a link / download a file / run any software unless you trust the source.
Contact us for guidance on how to safely inspect products like these.

For some commercial products we recommend, see Endorsements.
(contains paid advertising links)

We provide Excel Add-Ins which complement various spreadsheet projects.

Our Core Excel Add-In provides general utilities for advanced spreadsheet users, such as inspecting and manipulating formulas, tables, and metadata like Named Ranges and Conditional Formatting. It also provides abstract VBA facilities and helper functions.

Download the Core Add-In here:
pvCore.xlam
We recommend this ribbon menu to begin: ♠PV / AddIn / README

Our updated version of the old "Office2007IconsGallery" file is available here:
pvOffice2007IconsGallery.xlsx
We've removed all macros/executables in the interest of security.

Contact us for access to pvDEV, our advanced harness for developing Excel Add-Ins.

To complement our healthcare consulting and projects, we offer an ICD-10-CM interface which helps to navigate the large codebase:
ICD-10-CM SuperBill

To complement our cloud consulting and projects, we offer custom web-browser extensions.

This Chrome extension shows the default time-zone in Google Calendar:
Just Know your Zone

Contact us for information about our GMail Multi-Label extension.

One organization which administers commercial bar-codes is gs1.org.
They publish rules for calculating the final "check-digit" of certain bar-codes.

Here are two versions of a spreadsheet implementing those rules,
permitting bulk calculation of many barcodes at once:

• PVIS gs1.org check-digit Google spreadsheet
• PVIS gs1.org check-digit Excel spreadsheet

See the gs1 website for more information about this calculation:
https://www.gs1.org/services/check-digit-calculator

We specialize in financial analytics over a broad range of data sources.

Contact us for information on our extensive tools for integrating Bloomberg data with Excel spreadsheets.

This TradingView Indicator calculates PSAR (Parabolic Stop-and-Reverse) of any arbitrary metric:
TradingView PSAR of Custom Series

Here is a TradingView implementation of "High Jump," a technical indicator developed by the illustrious Ian Woodward of HGSI:
TradingView HGSI High Jump
see also:
HGSI High Jump

At Presidio Vantage, we specialize in the XML data model.
Here is a tool to partition and label text in HTML documents,
preserving hierarchy in a structurally-aware manner.
It is a relatively lightweight SAX implementation in Python.
HTML Cleaver

In particular, this logic was adapted for LangChain to build context-aware LLM applications over HTML data. See their blog post:

• A Chunk by Any Other Name:
  Structured Text Splitting and Metadata-enhanced RAG

Presidio Vantage provides some basic cryptographic services.

As part of an educational exploration of crypto-certificates,
we developed this colorized rendering of the SHA256 digest,
adapted from a monochrome vector image freely-available online.

• SHA256 Calculator: pvSHA256-text.xhtml
• SHA256 Border: pvSHA256-border.svg

We often build Spreadsheets to support business workflows.

This workbook assigns Vendors to Sales Reps in a weekly rotation,
covering every Vendor every week and shuffling Reps.

• Contact Schedule