ExcelGuide
Excel Reports That Finance Teams Rely On Month After Month
What makes an Excel report dependable for finance: reconciliations, rounding, controls, evidence, invoices, budgets, timesheets and currencies.
16 min read
Library
Everything you need to level up your coding skills.
CSVGuide
CSV Security Risks That Catch Teams Out and What to Do
How a CSV file hurts a team: formula injection, hostile uploads, leaked personal data, hidden payloads and risky loaders, with a fix and a check for each.
17 min read
YAML
Converting YAML to JSON in Python Without Date Errors
Convert YAML to JSON with PyYAML and json, and handle the cases that break it: dates, sets, integer keys, NaN, anchors, several documents and complex keys.
6 min read
Excel
Giving Users a Template Instead of Rules for Uploads
Replace a page of upload rules with a ready template: built-in formats, dropdowns, an example row, a stable link and a note on what the file is for.
7 min read
CSV
Opening a CSV With More Than a Million Rows in Excel
Excel stops at 1,048,576 rows and drops the rest if you save. Four ways to work with a bigger CSV: aggregate it, split it, use the Data Model or sample.
6 min read
JSONGuide
Handling JSON Files Too Large to Parse With Ordinary Tools
A tested guide to JSON files too big to load: memory and string limits, array to JSON Lines, DuckDB, streaming, splitting, compression and databases.
18 min read
XML
Merging Several XML Files Into One Valid Document Safely
Why cat breaks XML, and three ways that work: XInclude with xmllint, XSLT with document(), and lxml, with the xml:base attribute side effect of XInclude.
7 min read
CSV
Keeping Long Numbers Intact When Excel Opens a CSV
Excel keeps 15 significant digits, so a 19 digit ID loses its last four. Why it happens, how to import the column as text, and how to check a file for damage.
6 min read
Excel
Rejecting Files That Do Not Match the Template Cleanly
Reject Excel files that do not match the template in a way senders can act on: staged checks, stable codes, specific messages, quarantine and a retry path.
7 min read
CSV
Excel CSV UTF8 Versus CSV Comma Delimited Explained
Excel offers five CSV-like save formats. Here is what each writes, why plain CSV Comma Delimited loses characters, and which one to pick for each reader.
6 min read
XML
Counting Nodes in XML From the Shell Without Miscounting
grep counts lines, not elements. Count XML elements correctly with xmllint, xmlstarlet and a streaming parser, and see why grep gave 20000 for 49819 lines.
6 min read
YAML
Converting YAML to JSON With yq and Back Again Cleanly
yq converts YAML to JSON and back in one command. The same file gave different JSON in yq and PyYAML, and a big integer made yq fail. Flags and traps.
6 min read
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