Does Start of Month upload my file or text to Tool-You servers?

No. Start of Month runs in this browser tab. Files stay on the device. Limit note: Local calendar. Weekday names are English short forms.

Should I use End of Month instead of Start of Month?

Use Start of Month when you need First day of the month plus weekday. Use End of Month when you need Last day of the month plus weekday and day count. They share a category (Date & time) but not the same job.

Start of Month

First day of the month plus weekday.

Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.

What Start of Month does

Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.

This URL is only for Start of Month (datetime · start of month). First day of the month plus weekday. Other Date & time tools on Tool-You look similar in the chrome, so the job definition below is the part that belongs to Start of Month alone: Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.

How to use Start of Month

Confirm you need Start of Month, not End of Month (Last day of the month plus weekday and day count.). Address: /datetime/start-of-month.
Enter the numbers or dates Start of Month uses. First day of the month plus weekday.
Read the result as Start of Month defines it — not as Days in Month (Days in a month; leap flag for February.). Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.
Start of Month is an estimate in the browser, not professional advice. Local calendar. Weekday names are English short forms.
Need a different formula? Try Days in Month (Days in a month; leap flag for February.) instead of stretching Start of Month.

When not to use Start of Month

Skip Start of Month when a neighbor tool matches better — start with End of Month or Days in Month — or when the description already warns the job will fail. In the tool’s own words: Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.

Questions about Start of Month

What does Start of Month do that other Date & time pages on this site do not?: Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail. Short version: First day of the month plus weekday.
Does Start of Month upload my file or text to Tool-You servers?: No. Start of Month runs in this browser tab. Files stay on the device. Limit note: Local calendar. Weekday names are English short forms.
Should I use End of Month instead of Start of Month?: Use Start of Month when you need First day of the month plus weekday. Use End of Month when you need Last day of the month plus weekday and day count. They share a category (Date & time) but not the same job.
What are the limits of Start of Month?: Local calendar. Weekday names are English short forms. Also: Returns the first local calendar day of that month and a short weekday name. Unlike End of Month this is day 1. Invalid dates fail.