Open Source Survey Software
Survey responses are unusually sensitive data: they pair candid, sometimes unflattering opinions with the personal details of whoever gave them, which is exactly the combination people expect you to protect. Hosted form tools store that data on their servers and often cap how many answers you can collect before the price jumps. The open source options here let you run the questionnaires and keep every response on infrastructure you control, so honest answers never quietly become a third party's dataset. Because the code is open, you can also see how anonymity is actually implemented - what gets logged, what admins can see - instead of trusting a promise printed above the submit button.
PostHog
Open source product analytics platform with session replay, feature flags, experiments, surveys, and data pipelines
Formbricks
Open source experience data hub for in-app, website, link, and email surveys
HeyForm
Open-source form builder for surveys, quizzes, polls, and conversational forms
LimeSurvey
Open-source survey platform for creating questionnaires, polls, and forms with branching and multilingual support
TDuck
Privatizable survey and form system with drag and drop design, analysis, and webhook sync
Nextcloud Forms
Self-hosted surveys and questionnaires for Nextcloud with CSV export and private responses
KoboToolbox
Survey data collection and management platform with an API for forms, reports, and exports
Concerto Platform
Open-source online adaptive testing platform for building and running assessments
Our picks
Best for rigorous research surveys: LimeSurvey LimeSurvey handles unlimited surveys and questions with 30-plus question types, skip logic, and branching, and runs in more than 80 languages. Distribution covers closed-access mode, public links, and QR codes, and a RemoteControl API plus SAML and LDAP integrations suit institutional use. A strong default when you need serious questionnaire logic without vendor lock-in.
Best for in-product experience surveys: Formbricks Formbricks is a privacy-first experience platform for in-app, website, link, and email surveys, with a no-code editor and templates that target specific user groups without changing application code. It self-hosts with Docker and connects to Slack, Notion, Zapier, and n8n, a fit for gathering feedback at points in the user journey.
Best for field data collection: KoboToolbox KoboToolbox is a data-collection platform widely used by humanitarian and development organizations for surveys, monitoring, and evaluation. It provides a question library, sharing settings, reports, and CSV exports, and exposes a REST API for accessing data and managing forms. It stores data in Postgres and is self-hostable when respondent data must stay in-house.
Best for adaptive assessments: Concerto Platform Concerto Platform is an adaptive testing system that adjusts item difficulty per respondent using item-response-theory and computerized-adaptive-testing algorithms, with R available for scoring logic. Maintained by the University of Cambridge Psychometrics Centre, it authors and delivers tests in the browser and self-hosts from a Docker image, the pick when you need psychometric assessments, not plain surveys.
Where survey tools break under real questionnaires
Skip logic is where survey tools quietly diverge, so build one deliberately awkward pilot before you commit - required fields, conditional pages, piped answers, a disqualification path, and a repeated section. A tool that feels effortless with ten flat questions can turn brittle when respondents need different routes through the same instrument. LimeSurvey offers 30-plus question types with skip logic and branching across 80-plus languages, while Concerto Platform goes further into adaptive testing with item-response-theory scoring if you are running assessments rather than simple surveys.
Decide what identity means for each survey and how privacy is enforced. Public links, one-time invitation tokens, embedded widgets, and authenticated employee surveys create different fraud and anonymity problems, and a tool can support anonymous responses while still storing IP addresses, tokens, or delivery logs. Formbricks is privacy-first and can target in-app or link surveys, and Nextcloud Forms keeps everything inside your own Nextcloud instance. If anonymity is a promise, verify what is stored and whether contact records can be kept separate from answers.
Treat the response database as the thing you are really buying into. Good survey software preserves raw answers, timestamps, language, completion status, and stable question and choice codes in its exports, not just tidy charts. KoboToolbox exposes a REST API and CSV exports built for field research, and TDuck offers CSV export plus webhooks for add, change, and delete events. Confirm the same data the dashboard shows comes out through CSV, JSON, or an API, and test what a mid-study question edit does to past responses before a high-stakes survey launches.
Related categories
Frequently asked questions
How does respondent anonymity actually work in these tools?+
Anonymity is a mix of configuration and data handling, not a single switch. A tool can record anonymous answers while still storing IP addresses, invitation tokens, timestamps, or email delivery logs. Formbricks is built privacy-first, and Nextcloud Forms keeps responses inside your own instance, but you should still verify what admins can see and whether contact records can be separated from answers. Document those settings before the survey opens.
What survey logic should I test before choosing?+
Test the logic that could break your real survey. Build conditions from earlier answers, multi-select branches, calculated scores, hidden fields, quotas, page jumps, and a disqualification screen. LimeSurvey and Concerto Platform handle complex instruments, but the real test is editing a question after collecting responses and watching what happens to reports and exports. Tools vary widely in how safely they handle changes after launch.
How is survey software different from a basic form builder?+
Survey software is built around research-style instruments - skip logic, quotas, anonymity controls, invitations, partial responses, and exports that preserve question and answer codes. HeyForm and TDuck lean toward conversational forms and business data collection, while LimeSurvey and KoboToolbox target rigorous research and field work. If your results need analysis and defensible collection rules, use survey software rather than stretching a generic contact form.
Which of these handle offline field data collection?+
Offline capture matters for clinics, events, schools, and areas with weak connectivity. KoboToolbox is widely used for humanitarian and development field data collection and is designed around that workflow. When you evaluate offline mode, test local draft storage, on-device encryption, and what happens when one device collects many responses before reconnecting, since sync conflicts there directly affect the integrity of your final dataset.
Can a survey tool double as product analytics?+
Sometimes the two overlap. PostHog includes surveys alongside product analytics, session replay, feature flags, and experiments, so in-product feedback sits next to behavioral data. That is powerful if you already want an analytics stack, but heavier than a dedicated survey tool if all you need is questionnaires. Match the tool to whether feedback is a standalone program or part of a broader product-analytics setup.
What export formats protect ownership of my responses?+
At minimum, require CSV exports for responses plus a separate export of the survey structure with stable question IDs and choice codes. KoboToolbox provides a REST API and CSV exports, and TDuck adds webhooks and API sync for downstream systems. JSON helps with migration and automation. Reports alone are not enough - you want raw data that can be reprocessed without the original application running.
Do these surveys work well on phones?+
Many respondents answer on phones, so mobile rendering shapes data quality, not just looks. Test long matrix questions, ranking controls, file uploads, required fields, and progress indicators on a small screen, since a survey that abandons halfway on mobile biases your results. Nextcloud Forms and Formbricks are built to render cleanly on mobile, but always test your own longest, most complex questions.