SurveyCTO - Collect data you can trust Offline or online, in the field, on the street, or in the lab.
Scrapy - Scrapy | A Fast and Powerful Scraping and Web Crawling Framework
CommCare - The digital platform for impactful frontline work everywhere
StormCrawler - StormCrawler is an open source SDK for building distributed web crawlers with Apache Storm.
DHIS2 - Manage aggregate data with a flexible data model which has been field-tested for more than 15 years.
Apache Nutch - Apache Nutch is a highly extensible and scalable open source web crawler software project.