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Calculators, converters, PDF, text, images and much more — each with its own page. Type your data and get the result right here, with no sign-up and without your data leaving your device. Need them in your own app? The same tools are available by API.
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➗ MathFree
Arcsin calculator
The inverse sine of 0.5 is 30 degrees, or 0.523598775598 radians. Enter any value from -1 to 1 and get the one angle between -90 and 90 degrees with that sine…
A
Runs in your browser
➗ MathFree
Arctangent calculator
Enter the ratio 1 and get its arctangent: 0.785398163397 radians, which is 45 degrees. Any finite number works, however extreme, and the angle always stays…
A
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➗ MathFree
Arcus tangent calculator
The arcus tangent of 1 is 45 degrees, and of −1 it is −45 degrees. Unlike the inverse sine or cosine, it accepts any finite number, and you choose whether the…
A
Runs in your browser
➗ MathFree
Area calculator
A circle with a radius of 2 covers 12.566371 square units, and a 5-by-3 rectangle covers 15. Pick a square, rectangle, triangle or circle, enter only the…
A
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➗ MathFree
Oblique triangle area calculator
Two sides of 5 and 8 with a 60-degree angle between them enclose about 17.320508 square units. Enter the two sides and the angle they form, and get the area of…
A
Runs in your browser
➗ MathFree
Obtuse triangle area calculator
A base of 10 with a height of 4 gives an area of 20. Enter a base and its height, or the three sides, and from sides the calculator first proves the triangle is…
A
Runs in your browser
➗ MathFree
Area of a circle calculator
A circle with a radius of 5 has an area of 78.539816, computed with the full value of π, 3.141592653589793, never a rounded 3.14.
A
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➗ MathFree
Area of a trapezoid calculator
Bases of 10 and 6 with a height of 4 give an area of 32: add the two parallel sides, halve the sum and multiply by the height.
A
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📏 Unit convertersFree
Look up paper size dimensions in mm and inches
Type a paper name and get its exact size in millimetres and inches: A4 is 210 by 297 mm, Letter is 8.5 by 11 inches.
M
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📏 Unit convertersFree
Convert shoe size between US, UK, and EU regions
Get all three labels for one adult shoe size at once: a men’s US 9 is a UK 8 and an EU 42.5. Pick the system printed on the box and men or women, and half sizes…
R
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🏠 Home, food & hobbiesFree
Child allowance calculator by age
With the common rule of one unit per year of age, a 10-year-old gets 10 a week, which adds up to 520 a year and an average of 43.33 a month.
B
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📄 Documents & PDFFree
PDF booklet imposition calculator for saddle-stitch printing
A 10-page PDF becomes a 12-page booklet on three sheets, with the two blanks on the outer sheet beside pages 1 and 2.
B
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📄 Documents & PDFFree
Add a PDF bookmark
In a 32-page PDF with Cover on page 1, Methods on 8 and Appendix on 27, a Results bookmark for page 18 lands third, between Methods and Appendix.
B
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📄 Documents & PDFFree
List PDF bookmarks
A bookmark tree with Preface, Part I and Appendix on top and three headings nested under Part I becomes six rows with title, level and page, children right…
B
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📄 Documents & PDFFree
Compare two PDFs by text
A revenue figure edited from 2.4 to 2.7 million on page 1, two words added on page 3 and a new page 4: exactly those three pages are flagged, with the words…
F
Runs in your browser
📄 Documents & PDFFree
Crop PDF pages
On a 612 by 792 point Letter page, a crop box from 36, 54 measuring 540 by 684 fits and leaves exactly that visible area.
F
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📄 Documents & PDFFree
Estimate PDF font subsetting savings from glyph usage
A font with 2,048 glyphs that a PDF uses for only 180 distinct characters could shed about 91.21% of its glyph data.
R
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📄 Documents & PDFFree
Parse a PDF page range string into page numbers
Type 1-3,5,8-10 and get pages 1, 2, 3, 5, 8, 9 and 10, each once and in the order you wrote them. Every page is checked against the document's real page count…
K
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📄 Documents & PDFFree
List images in a PDF
A page 2 holding a 1200 × 800 photo and a 64 × 64 icon becomes two tidy rows, each with page, image number, width and height.
F
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📄 Documents & PDFFree
Extract text from PDF pages
Two page texts, a quarterly report and its appendix, become one document with a clear --- PAGE BREAK --- marker between them, in the order you supplied and with…
F
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📄 Documents & PDFFree
Validate PDF form fields and required values
Before a form is filled, Ada Lovelace's name, a birth date of 1815-12-10 and the email choice are checked against four field rules, and the unanswered…
B
Runs in your browser
📄 Documents & PDFFree
Flatten PDF form fields into static page content
Ada (Countess) Lovelace typed in a text box on page 1 and a ticked box on page 2 become fixed page content, and the report confirms both were flattened.
B
Runs in your browser
📄 Documents & PDFFree
Convert PDF to grayscale
Four pages marked color, grayscale, CMYK and grayscale come back as four grayscale pages, with a count showing that 2 of them actually needed a change.
F
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📄 Documents & PDFFree
Convert images to PDF
A 2400 × 3000 scan at 300 DPI becomes a 576 × 720-point portrait page with a 4:5 ratio, while a 1920 × 1080 photo becomes a 16:9 landscape page.
B
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📄 Documents & PDFFree
Insert a blank PDF page at any position
Choose position 2 and a clean page appears between the first and second pages of your PDF, sized like the page it lands before, taking the document from 2 to 3…
F
Runs in your browser
📄 Documents & PDFFree
Check PDF linearization and fast web view status
Tell it the inspector found the PDF linearized and you get a ready-to-file finding: fast web view supported, what that means for first-page display, and the…
B
Runs in your browser
📄 Documents & PDFFree
List PDF form fields
A four-field form comes back as a tidy inventory: a text box holding Ada Lovelace, a ticked checkbox, a dropdown set to United Kingdom and a signature field…
B
Runs in your browser
📄 Documents & PDFFree
Merge PDF files online in the order you choose
Join a two-page agreement, a four-page schedule and a one-page signature sheet into one PDF, in exactly the order you list them, and see the total: seven pages.
F
Runs in your browser
📄 Documents & PDFFree
N-up PDF pages
Put 4 pages of 612 × 792 points on one sheet and you need a 1224 × 1584 sheet with two columns and two rows.
B
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📄 Documents & PDFFree
Overlay two PDFs
Preview what each stacked page will hold before you build the file: an invoice page under an APPROVED stamp, paired page by page, base below and overlay on top.
B
Runs in your browser
📄 Documents & PDFFree
Count PDF pages
Get a page total and the first page's size from the page sizes your PDF reader has already found: three pages, the first one 612 × 792 points.
F
Runs in your browser
📄 Documents & PDFFree
Build a PDF page thumbnail grid layout
A 23-page PDF laid out in five columns needs five rows, offers 25 cells and puts three thumbnails in the last row.
M
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📄 Documents & PDFFree
Set PDF permissions
Give it PRINT, print, copy and an annotate with stray spaces, and you get back print, copy, annotate: one clean permission set in a fixed order, with no…
B
Runs in your browser
📄 Documents & PDFFree
Redact text in PDF
Enter falcon once and all three forms in a sentence, Falcon, FALCON and falcon, become ████, with a count of 3 to prove it.
B
Runs in your browser
📄 Documents & PDFFree
Remove blank PDF pages and count the pages left
Tell it which of five pages have text or images and you learn that pages 2 and 4 are blank: two pages go and three remain.
B
Runs in your browser
📄 Documents & PDFFree
PDF Repair Diagnostic
Enter three findings, such as a missing cross-reference table, an unterminated stream and an unexpected end of file, and learn that two are fixable and one is…
B
Runs in your browser
📄 Documents & PDFFree
Resize PDF page size
A US Letter page of 612 by 792 points fits on A4 at a scale of 0.972673, keeping its proportions and leaving equal margins at the top and bottom.
F
Runs in your browser
📄 Documents & PDFFree
Rotate PDF pages 90, 180, or 270 degrees
Choose pages 1,3-5 and a 90-degree turn, and only those four pages rotate while page 2 stays as it is.
G
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📄 Documents & PDFFree
Set PDF metadata
A title typed with extra spaces comes back as Quarterly Report, and the keywords Finance and finance merge into one, keeping the first spelling.
NA
Runs in your browser
📄 Documents & PDFFree
Explain PDF digital signature status and trust warnings
A signature that passes the check on an unchanged PDF, but from an unknown signer, comes back as needs review: the document may be intact, yet the signer's…
B
Runs in your browser
📄 Documents & PDFFree
Split PDF by page range into a new file
Ask for pages 4 through 7 and you get a new four-page PDF with exactly pages 4, 5, 6 and 7, in their original order.
F
Runs in your browser
📄 Documents & PDFFree
Split PDF every N pages into consecutive files
Split an eleven-page PDF every four pages and you get three files: pages 1–4, 5–8 and 9–11, the last one shorter, with no blank pages added and none dropped.
F
Runs in your browser
📄 Documents & PDFFree
Strip PDF metadata
Give it the metadata read from a PDF, such as Title, Author, Creator, CreationDate and an internal tracking number, and it comes back empty with a sorted list…
F
Runs in your browser
📄 Documents & PDFFree
Generate a PDF table of contents from bookmarks
Five bookmarks, from Introduction on page 1 to Reference on page 27, become a finished contents page with indented sub-entries, dot leaders running to each page…
B
Runs in your browser
📄 Documents & PDFFree
Extract PDF multi-column text in correct reading order
Four shuffled blocks from a two-column page come back as left first, left second, right first and right second.
F
Runs in your browser
📄 Documents & PDFFree
PDF to EPUB chapter structure from bookmarks
Five bookmarks with Preface, Part One and Appendix at the top level become three EPUB chapters, named chapter-001.xhtml to chapter-003.xhtml, while nested…
B
Runs in your browser
📄 Documents & PDFFree
PDF to image sequence
Enter 12 pages and PNG and you get page-01.png through page-12.png, one name per page, with enough leading zeros that page-10 never sorts before page-2.
B
Runs in your browser
🏠 Home, food & hobbiesFree
Pet life stage calculator
A large dog of 8 is already a senior: large breeds become adults at 1.25 years and seniors at 7. Cats follow one schedule, kittens until 1 and seniors from 11…
B
Runs in your browser
🏠 Home, food & hobbiesFree
Calculate next pet vaccination due date
A canine DHPP shot given on 2024-02-29 is next due on 2027-02-28: the 36-month interval is added as calendar months, and a missing day falls back to the end of…
K
Runs in your browser
🔬 ScienceFree
Acceleration due to gravity calculator
At 10 km, around a long-haul cruising altitude, gravity is about 0.3 % weaker than the standard 9.80665 m/s² at sea level.
H
Runs in your browser
🔬 ScienceFree
Acceleration of a charged particle in an electric field
A particle carrying 0.000002 C with a mass of 0.001 kg in a 5000 N/C field accelerates at 10 m/s².
H
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🔬 ScienceFree
Acceleration calculator
A force of 20 N on a 5 kg mass gives an acceleration of 4 m/s². Enter the net force in newtons and the mass in kilograms; a negative force returns a negative…
H
Runs in your browser
🔬 ScienceFree
Acoustic impedance calculator
Air at 1.204 kg/m³, with sound at 343 m/s, has an acoustic impedance of 412.972 Rayl. Enter a medium's density and speed of sound to get the figure that decides…
H
Runs in your browser
🔬 ScienceFree
Air density calculator
At 1013.25 hPa, 15 °C and 60 % relative humidity, air weighs 1.220312 kg per cubic metre, a little less than the textbook 1.225 for dry air.
H
Runs in your browser
🔬 ScienceFree
Air pressure at altitude calculator
At 1,500 m the standard atmosphere puts the air pressure at 845.562621 hPa, against 1013.25 hPa at sea level.
H
Runs in your browser
🔬 ScienceFree
Alfvén velocity calculator
A 0.00005 T field in a plasma of 1.67 × 10⁻¹³ kg/m³ gives an Alfvén velocity of 109145.751826 m/s, more than 100 km per second.
H
Runs in your browser
🔬 ScienceFree
Alien civilizations calculator
With 1.5 stars born per year, planets around every star, 0.4 habitable worlds each, life wherever possible, 0.1 for intelligence, 0.2 for communication and a…
H
Runs in your browser
🔬 ScienceFree
Temperature at altitude calculator
If it is 20 °C at sea level, expect about 10.25 °C at 1,500 m, since the standard atmosphere loses 6.5 °C every 1,000 m.
H
Runs in your browser
🔬 ScienceFree
Amp to wire size calculator
A 20 A load on a 30 ft run at 12 V, allowing a 3 % drop, needs 4 AWG copper. Enter current, one-way length, voltage and drop budget to get the smallest gauge…
H
Runs in your browser
🔬 ScienceFree
Angle of incidence calculator
A ray going from index 1 into glass of index 1.5 at 30° continues at 19.4712206345° from the normal.
H
Runs in your browser
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1
Get your key
Create an account with your email and add balance when you need it. No subscription, no sales call.
2
Call the endpoint
One authenticated POST. The API returns a task_id immediately — copy-paste snippets in five languages on every page.
3
Collect the result
Receive a signed webhook the moment it's ready, or fetch a signed link. A failed task is never charged.
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On-device utilities — hash, QR, JSON, Text→PDF and more — run in your browser. No account, no limits.
Pay-as-you-go
Per task
$0.002+
The full API — 7800+ capabilities — billed only for what you run, from $0.002 per call. No monthly fee.
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Top up your balance and spend it across web, API and the app. It never expires.