Processed in your browser
Images are decoded, resized, cropped and re-encoded by the Canvas API on your own machine. Resume data is saved in your own browser storage and the PDF is generated on your device.
Free online tools
Powerful tools for developers, creators and everyday work.
Format JSON, compress images, edit PDFs, build resumes, create mock APIs and more — fast, simple and privacy-friendly.
Try “compress”, “jpg to png”, “resume”, “json” or “mock api”.
Why use ToolDuck
- Free to use Every tool is free. No trial, no paywall, no usage cap on the file tools.
- Privacy-friendly Image and resume tools work on your device, so the file is never uploaded.
- Fast Local processing means no upload wait and no queue — results appear as you type.
- Developer-friendly Real utilities for real workflows: JSON, diffing, and an API to build against.
Popular tools
Start with the tools developers and creators use most.
JSON Formatter
Format, validate, repair and explore JSON directly in your browser.Use toolMock API
Create a free mock API endpoint and get a public URL in seconds.Use toolImage Compressor
Compress JPG, PNG and WEBP images online without visible quality loss.Use toolImage Converter
Convert images between JPG, PNG and WEBP in bulk.Use toolImage to PDF
Combine JPG, PNG and WEBP images into a single PDF.Use toolCreate Your Resume
Upload the resume you already have and get a clean, ATS-friendly PDF back — or build one from scratch.Use toolATS Resume Checker
Check your resume for the layout and content problems parsers trip over.Use toolJSON Compare
Compare two JSON documents and see exactly what changed.Use toolNo tools match that search yet. Try “compress”, “convert”, “resize”, “resume”, “json” or “api”.
Explore tool categories
Everything organised in one place.
Image Tools
11 toolsCompress, resize, convert, crop and merge images.Browse toolsPDF Tools
Coming soonMerge, split, compress and edit PDF documents.Coming soonResume Tools
4 toolsBuild, check and improve your resume.Browse toolsDeveloper Tools
3 toolsHandy utilities for developers.Browse toolsIn progress: Security & encoding tools · Text & case converters · Unit & date converters
Mock API
Create a mock API in seconds
Build a temporary API endpoint for frontend development, mobile apps, demos and automated testing. Define the response, choose the HTTP method and get a public URL instantly.
- Any method, status code, headers and delay
- Dynamic values such as
{{uuid}}and{{path.id}} - Scenarios to switch an endpoint between success and failure
- A request log with masked headers, so you can see what your app sent
GET /mock/abc123/users 200 OK · 24 ms[ { "id": 1, "name": "Jane Cooper", "email": "jane@example.com" } ]
Developer tools without the busywork
Small utilities for the repetitive tasks that slow development down.
- Base64 encoder / decoder Planned
- URL encoder / decoder Planned
- JWT decoder Planned
- UUID generator Planned
- Hash generator Planned
- Timestamp converter Planned
Image tools that just work
Compress, resize, convert and crop without uploading anything. Everything here runs in your browser, so a 20 MB photo is processed on your own device.
Image Compressor
Compress JPG, PNG and WEBP images online without visible quality loss.Use toolImage Resizer
Resize images by pixels or percentage with social media presets.Use toolImage Converter
Convert images between JPG, PNG and WEBP in bulk.Use toolPNGJPG to PNG
Convert JPG photos to lossless PNG images.Use toolJPGPNG to JPG
Convert PNG images to smaller JPG files.Use toolWEBPJPG to WEBP
Convert JPG to modern WEBP for faster websites.Use toolWEBPPNG to WEBP
Convert PNG to WEBP and keep transparency.Use toolJPGWEBP to JPG
Convert WEBP images back to universally supported JPG.Use toolResume tools, and PDFs on the way
Build a resume, choose a template, check how well hiring software can read it, and match it against a job description. Your details stay in your browser.
Resume builder
Create Your Resume
Upload a resume, review what was read, and download a professional PDF.
- Import a PDF, DOCX, TXT or Markdown file and edit it instead of retyping
- Live preview with print-ready templates, exported as a clean PDF
- Your details stay in your own browser — nothing is uploaded
PDF tools are coming next
Merge, split, compress and edit PDF documents. The first of these is already available as an image to PDF tool.
Your files stay yours
Many of our browser-based tools process data locally on your device, so there is no upload step and nothing on a server to leak, log or delete. The Mock API is the one exception, and it says so on its own page.
- Your device
- ToolDuck in your browser
- Processed locally
Fast, because nothing travels
Uploading a 20 MB photo over a phone connection takes longer than processing it locally. Working on the device means results appear immediately instead of waiting in a queue.
No tracking by default
Analytics stay switched off until they are explicitly enabled, and the ad placeholders are kept away from the tool controls. The file tools need no account, so there is nothing to sign up to.
Free online tools for developers and everyday tasks
ToolDuck is a collection of free online tools for the small, repetitive jobs that interrupt real work: shrinking an image so a page loads faster, converting a screenshot into a format an upload form will accept, reformatting a wall of JSON until it can be read, or building a resume that hiring software can actually parse.
There is no sign-up in front of the file tools and no daily cap on how many times you can use them. Open a page, drop in a file, take the result. That is the whole interaction, and it is deliberate — a utility you have to register for is a utility you stop using.
Developer tools
The JSON formatter does more than add indentation. It validates as you type and reports the exact line and column of a syntax error, which is the part that actually costs time when something is broken. The JSON compare tool shows what changed between two documents instead of making you read both.
Mock API is the part of ToolDuck that is a product rather than a utility. It gives you a public HTTPS endpoint that returns the JSON you configure — with the method, status code, headers and delay you choose — so an Android, iOS, Flutter or web app can be built against a real URL before the real backend exists. It is also the easiest way to produce failure on purpose: a 503, a two-second delay, or an endpoint that changes its mind on the second call, without touching application code.
Image tools
The image compressor and image resizer are the two most used tools on the site, followed by the image converter for moving between JPG, PNG and WEBP. There are single-purpose pages for the common directions — JPG to PNG, PNG to JPG and the WEBP conversions — because "convert this file" and "convert between these two formats" are different intents, and a page that does only the one thing you asked for is quicker to use.
All of it runs in the browser using the Canvas API. That has two consequences worth stating plainly: your images are never uploaded, and the tools keep working if you lose your connection after the page has loaded.
Resume tools
The resume builder reads an existing resume in the browser to fill its own form, so you are editing rather than retyping. From there you can switch between ATS-friendly templates, run an ATS resume check to see how hiring software reads the layout, and match the wording against a job description before you apply. Your details live in your own browser storage and the PDF is generated on your device.
Browser-based tools, and what that means
"Browser-based" is not a marketing word here. It means the work happens on your machine using APIs the browser already has: Canvas for images, local storage for resume data, and the built-in encoder for PDF generation. Nothing is sent to a server, nothing is queued, and nothing waits on an upload.
It also means an honest limit. Very large batches depend on your device's memory rather than ours, which is why a single image is capped at 25 MB and a batch at 20 files. Those are browser limits, not server limits.
Browse by category
- Image tools — compress, resize, convert, crop and turn photos into a PDF.
- Developer tools — format and validate JSON, compare two documents, build a mock API.
- Resume tools — build, template, check and keyword-match a resume.
- All tools — the complete index, filterable by name.
If a tool you need is missing, the contact page is the place to say so. The site is built one useful tool at a time, and the ones that get built next are the ones people ask for.
All 18 tools
Every tool on ToolDuck, grouped by what it does.
- Mock API Developer Tools
- Image Compressor Image Tools
- Create Your Resume Resume Tools
- JSON Formatter Developer Tools
- Image Resizer Image Tools
- Resume Templates Resume Tools
- JSON Compare Developer Tools
- Image Converter Image Tools
- ATS Resume Checker Resume Tools
- JPG to PNG Image Tools
- Resume Keyword Matcher Resume Tools
- PNG to JPG Image Tools
- JPG to WEBP Image Tools
- PNG to WEBP Image Tools
- WEBP to JPG Image Tools
- WEBP to PNG Image Tools
- Image Cropper Image Tools
- Image to PDF Image Tools
Frequently asked questions
What is ToolDuck?
ToolDuck is a collection of free online utilities for developers, creators and everyday digital work. It covers image editing and conversion, resume building and checking, JSON formatting and comparison, PDF generation, and a mock API platform for testing apps against a real URL.
Are ToolDuck tools free?
Yes. Every tool is free to use, with no trial, credit card or usage limit, and the file tools need no account at all. The site is supported by advertising rather than subscriptions.
Do I need an account to use ToolDuck?
Not for the file tools. Compressing an image, converting a format, building a resume or formatting JSON needs no sign-up. The Mock API is the exception: a project has to belong to somebody, so it needs a free account with an email address and a password, or Google.
Is my data uploaded when I use ToolDuck?
For the image tools and the resume builder, no. They use the browser's own Canvas and storage APIs, so your files are read and rewritten on your device and are never sent to a server. The Mock API is different by design: it is a server, so the endpoints you configure and the requests made to them are stored and shown back to you in the request log. Nothing else on the site sends a file anywhere.
What developer tools does ToolDuck provide?
A JSON formatter that also validates and repairs, a JSON compare tool that shows exactly what changed between two documents, and a mock API platform for building endpoints your app can call before the real backend exists. Base64 encoding, URL encoding, JWT decoding, UUID and hash generators are in progress.
Can I create a free mock API with ToolDuck?
Yes. Create a project, add endpoints with a method, path, status code and response body, and you get a public HTTPS URL straight away. Responses support dynamic values such as {{uuid}} and {{path.id}}, plus delays, error statuses and multiple scenarios, so you can test failure and latency without changing your app.
Can I use ToolDuck on mobile?
Yes. Every tool is responsive, the image drop areas accept files from the photo library, the cropper handles are sized for touch, and the navigation collapses into a menu. Very large image batches are best processed in smaller groups on a phone.
Do the tools keep working offline?
The browser-based ones do, once the page has loaded. Image processing, resume building and PDF generation all run locally with no server round trip, so losing the connection changes nothing. The Mock API cannot work offline, because its whole purpose is to be reachable from somewhere else.
Ready when you are
No sign-up for the file tools. Pick one and get on with the thing you were actually doing.