
Codewars
Exercism
LeetCode
CodinGame
CodeCombat
HackerRank
Google's Python Class
CheckIO is a web site with a mission: To teach JavaScript and Python coding skills through a game-playing interface. It is designed to teach new skills or improve existing skills through completing challenges.

PDFShift
DocRaptor
pdflayer
HTMLEmail.io
PDFCrowd
Templates by Email Monster
PDF my URL
Developer-first file conversion and website capture API: 300+ format pairs across documents, images, audio, and video, plus pixel-perfect HTML-to-PDF rendering. Plain REST, no SDK required. 100 free conversions a month, files up to 1 GB.

Which is more popular?
Based on our record, CheckIO seems to be more popular. It has been mentioned 46 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | checkio.org | converterer.com |
| Pricing | — | |
| Platforms | — | |
| Company | — | Startup from Australia · 1 - 9 employees · 2018 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of CheckIO yet.
Converterer (formerly Paperplane) is a REST API for file conversion and website capture, built for developers and no-code workflows. File conversion: convert documents, spreadsheets, presentations, images, audio, and video across 300+ format pairs: DOCX to PDF, PDF to DOCX, XLSX to CSV, PNG to...
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
Intro Video. How to get maximum from CheckiO
Video Review Paperplane New Era 9FIFTY Snapback Cap
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing CheckIO and Converterer.
Converterer's answer:
Two APIs under one plan and one allowance: file conversion across 300+ format pairs (documents, spreadsheets, presentations, images, audio, video) and website capture that renders any URL as a print-ready PDF with a real headless Chromium engine. Pricing is flat per conversion, so a 900 MB video costs the same as a 40 KB document, where most competitors bill credits or processing minutes that scale with file size. And there is no SDK to install: it is plain REST you can drive from cURL.
Converterer's answer:
Predictable cost and less integration work. Flat per-conversion pricing with files up to 1 GB on every plan means no surprise bills when documents get heavy. The free tier is a real recurring allowance, 100 conversions every month with no card, rather than a one-time trial. Integration is one POST request with HTTP Basic auth, HMAC-signed webhooks instead of polling, and delivery straight into your own storage bucket if you want it. The capture engine has been rendering PDFs in production since 2018, and we publish sourced, dated comparisons against competitors on our own site, including the cases where they are the better fit.
Converterer's answer:
Developers adding file conversion or document rendering to their products (invoices, reports, archives, media processing), and operations or no-code builders automating the same jobs through Zapier, Make, n8n, Power Automate, or Workato. Typical users are SaaS teams generating documents at scale and teams replacing self-hosted conversion stacks they no longer want to operate.
Converterer's answer:
Converterer started in 2018 as Paperplane, a focused HTML-to-PDF API built on headless Chrome. Customers kept asking for conversions that had nothing to do with HTML: DOCX to PDF, HEIC to JPG, MP4 to GIF. So the platform grew past its name, and in May 2026 it relaunched as Converterer: the same team and rendering engine, expanded to a full file conversion API with 300+ format pairs alongside the original website capture.
Converterer's answer:
Website capture runs on a real headless Chromium engine, so output matches what desktop Chrome renders, including web fonts, Flexbox, Grid, and JavaScript-heavy pages. The API itself is plain REST over HTTPS with HTTP Basic authentication and HMAC-signed webhooks, and output delivery integrates with standard object storage (S3-compatible, Google Cloud Storage, Azure).
Share your experience with using CheckIO and Converterer. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


CheckiO is a platform with coding games created for different levels of programmers, from beginners to advanced levels. Using fun and engaging methods, you can use coding games to solve challenges in TypeScript and...
CheckIO is available in English and Spanish. The platform was designed by a group of engineers and now has a number of customers all over the globe who may use it to improve their programming speed and abilities by...
Checkio is the most whimsical HackerRank alternative on this list. It’s also focused on two languages: Python and TypeScript. On this site you’ll be thrown into a gamer’s paradise that includes robot mollusks and...
We have no reviews of Converterer yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


Have you heard of CheckIO (https://checkio.org/)? They have a gameified "Mario world" of coding challenges that are smaller and come with more explanation, tests to guide you through edge cases and provide hints. The challenges start... Source: almost 3 years ago
Cyber isn't gonna be a light switch, where you can flip it and be good. Don't be too hard on yourself. Start with some hands on stuff like https://tryhackme.com or checkio.org. You could look at certs like Security+ or CySA+ for some... Source: about 3 years ago
Much better to get your hands dirty than watching the videos. Try: https://checkio.org/. Source: over 3 years ago
Tracking Converterer since Mar 2021.
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