New this week

Blurs rectangles you draw on one or many images, with bulk download.

Groups pasted timestamps by day, week or month and charts them with range filters.

Designs vibration patterns with amplitude and smoothing settings and outputs the pattern data.

Calendar where you click to add, drag and copy events, saved in the URL so it can be shared.

Estimates the token cost of an image for OpenAI vision models from its width, height and detail level.

Turns Java package names into a visual folder tree.

Draws two- or three-circle Venn diagrams from comma-separated items.

Tabulates sun or moon altitude and azimuth through one day.

Tabulates hours of daylight and darkness through a year for a location.

Lists equinoxes, solstices, perihelion and aphelion for a given year.

Converts between calendar dates and Julian dates.

Lists dates and times of new, quarter and full moons for a chosen year.

Gives rise, set and transit times for the planets, Sun and Moon.

Gives sun and moon rise, set, twilight and phase for one day at a location.

Builds a yearly table of sunrise, sunset, moonrise and moonset for a place.

Computes Greenwich and local sidereal time for a date and time.

Computes local circumstances for solar eclipses at a chosen location.

Strip HTML tags, encode or decode entities, format HTML and compare two code snippets in a diff viewer.

Fits dose-response data to get an EC50 value and curve.

Fits a four-parameter logistic curve to assay data.

Fits dose-response data to get an IC50 value and curve.

Probes browser APIs to expose fingerprinting signals and detect spoofing or privacy tools.

Estimates the savings goal and earliest age you can retire early.

Plots a 3D surface from an equation z equals f of x and y that you type.

Estimates pi by randomly scattering points in a square and counting those in a circle.

Draws Lissajous curves from two sine waves with adjustable frequency and phase.

Shows AND, OR, NOT, NAND, NOR and XOR gate outputs as you toggle inputs.

Simulates a body orbiting a mass with adjustable starting speed and distance.

Rotates a shape around a chosen point and shows the new coordinates.

Shows the frequency spectrum of sound from your microphone or a test tone.

Displays audio from the microphone as an oscilloscope trace.

Maps a wavelength of light to its visible colour with a slider.

Free scan that audits a site for WCAG and ADA issues.

WCAG 2.0 AA and AAA contrast checker that suggests the nearest accessible color.

Mortgage payment including principal, interest, taxes and insurance, with an amortization table.

Tables, lists, tokens and scenery for D&D 5th Edition, gathered for quick lookup at the table.

Upload a PDF and Claude writes a flashcard deck from it, which you then practice through games, quizzes and an XP system.

Assessment that scores how mature an organization's AI adoption is, using Claude for the analysis.

Estimates the PCB trace width needed to carry a given current within a temperature rise.

Searchable catalog of Dungeons and Dragons adventures filterable by level, setting and publisher.

Gives exact age in years, months, days, hours and minutes from a birth date.

Lists top backlinks pointing to a domain or URL.

Finds broken links on a website.

Estimates how hard it would be to rank on page one for a keyword.

Suggests keyword ideas with search volume and difficulty for a seed term.

Shows the top Google results for a keyword with their key metrics.

Estimates organic traffic and top pages for a site.

Shows Domain Rating and basic link metrics for a domain.

Generates acronym ideas from a phrase or theme.

Estimates how likely a text was written by an AI model.