Learn how to solve classic puzzles, optimize client-side workflows, and protect your privacy with local-first browser tools.
Can't solve your 15-puzzle or 8-puzzle? Learn the 4-step method and corner techniques for solvable sliding tile puzzles. Includes illustrations, parity checks, and our free AI solver.
For business professionals working on monthly or annual salaries, we explain how to calculate your true hourly rate reflecting actual working hours and annual holidays, and check if you meet local minimum wage lines.
We explain how to calculate smart bill splitting (slanted distribution) that keeps everyone happy in groups with different consumption levels, and rounding techniques to prevent hassle at checkout.
``How many volumes of this manga did you buy?'' This is an article for manga collectors who worry when they see a new issue at a bookstore, or feel despair after buying the same volume more than once. We will introduce a free digital bookshelf that can be managed intuitively using cover images instead of text lists, does not require registration, and operates completely locally.
``Email header (raw source)'' is a record of the servers that an email went through before arriving. In this article, we will explain in detail the role of an email header analysis tool, identifying the delivery route and delay time using the Received header, how to read SPF/DKIM/DMARC judgments, and the procedure for completely local analysis safely without the risk of information leakage.
We will explain in detail how to determine social insurance premiums (health insurance, welfare pension, etc.), income tax, and resident tax that are deducted from your face value salary, and how to use a free simulation tool that allows you to instantly calculate the ``take-home pay'' you will actually receive.
Regarding ``OCR character recognition,'' which converts characters in images into text data that can be copied and pasted, we will explain in detail tips for dramatically increasing recognition accuracy, the differences from cloud OCR, and the advantages of offline OCR tools that can be performed safely using a browser.
We will explain in detail the causes of garbled characters when opening a downloaded CSV file in Excel, the difference between reopening it in Notepad and Excel's data import function, and the solution procedure for safely and easily converting the character code to Shift_JIS or UTF-8 completely using a browser.
Explaining the mechanism for calculating the ``maximum donation deduction amount (limit amount)'' that allows you to donate advantageously through hometown tax payments! We will introduce in detail how to calculate not only the annual income of salaried workers but also the income of self-employed business owners, the effect on the limit when using medical expense deductions and final tax returns, and how to use a simulator that allows you to safely calculate estimates without sending personal information externally.
Regarding the ``year of admission/graduation'' that is always confusing when creating a resume for job hunting or job-change activities, we will explain in detail the year discrepancy due to Ronin, repeating a grade, or being born early, basic manners for writing a resume (unifying Western and Japanese calendars, noting dropouts, etc.), and how to use automatic calculation tools.
We will explain in detail the legal effect and role of electronic seals, which are necessary with the spread of remote work and electronic contracts, as well as their role as authentication seals, the procedure for pasting them neatly onto Excel or PDF contracts, and how to create transparent PNG seals locally.
We will explain in detail the nature and merits of the image format ``HEIC'' taken with the iPhone, compatibility issues in the Windows environment, and the steps to safely convert all images to JPEG/PNG format on a browser without using the Internet.
As a countermeasure for when you cannot open an "M4A" file recorded with a smartphone's voice memo on a computer, etc., we will explain in detail the characteristics of various audio formats (MP3/WAV/WebM), how to choose an appropriate bit rate, and the procedure for safely converting audio within the browser without the need for communication.
Regarding PDF password protection, which is essential for businesses, we will explain in detail the difference between viewing passwords and privilege passwords, and the steps to set or cancel viewing restrictions and printing protection locally.
We will explain in detail the dangers of identifying personal information (reflections in your eyes, Exif location information, car license plate numbers, etc.) that you should be aware of before uploading photos to SNS, as well as the mosaic processing procedure to safely hide images with completely local processing without the risk of external leakage.
We will explain in detail the conditions for creating a ``secure and difficult-to-guess password'' to protect your online accounts from unauthorized access, hacker attack methods (dictionary attacks and brute force), current new security standards (does periodic change need to be done?), and how to use secure local automatic generation tools.
Initial display speed (LCP) is an issue for portal sites that aggregate useful tools into one domain. We will introduce a technical approach that improved the Lighthouse score using Next.js dynamic import and AdSense load optimization.
Understand browser-based image and PDF processing, external speech and data services, model downloads, local storage, and advertising or analytics requests.