Restack Open Call (2026-11R)

Restack Open Call (2026-11R) is a cascade funding opportunity under the Open Internet Stack initiative offering short R&D grants to develop open source software and open hardware building blocks for a resilient Open Internet Stack. Typical first-stage grants range from €5,000 to €50,000, the overall programme budget is €7,000,000, project durations are expected to be 1–12 months, and per-proposal and per-beneficiary lifetime ceilings exist (up to €150,000 and €500,000 respectively). The call is open to individuals and organisations with a clear European dimension, requires open access publication and recognised free/open-source licensing for outcomes, and has a strict generative AI disclosure policy. Submission is via NLnet's portal with a deadline for this call of 03 November 2026, 12:00 Brussels time.

What it funds

Scope

Small to medium R&D grants for development, validation and maturation of open-source internet commons across the technology stack (software and hardware), including security audits, packaging, documentation, standardisation, usability, testing infrastructure and related research. AI projects are out of scope unless already widely used (>€1Musers) and directly relevant to the stack.

Typical grant sizes:First-stage requests should be between €5,000 and €50,000; single-proposal maximum €150,000; maximum cumulative award per beneficiary over the programme €500,000. Total programme budget: €7,000,000 ¹.

Who can apply

Open to anyone, including private individuals, SMEs, NGOs, research institutions and other organisations. Proposals must have an EU/European dimension and be primarily R&D-focused; results (publications and code/hardware) must be open access and released under recognised free/open-source licences.

Key administrative facts

1. 1Deadline: 3 November 2026, 12:00 (Brussels/CET).
2. 2Expected project duration: flexible between 1 and 12 months.
3. 3Submission route: submit via NLnet propose form (see guide) Apply via NLnet.
4. 4Selection: two-stage review; scoring on technical merit (30%), strategic relevance/impact (40%), value for money (30%); must score >5.0/7 to pass.

Proposals must be concise (main application equivalent to two pages), written in English, and follow the Restack Guide for Applicants. There is a strict Generative AI disclosure and provenance requirement for any use of GenAI in proposals or project work. ¹

Footnotes

1. 1Full call text, application guidance and FAQ are available from NLnet Restack pages: nlnet.nl (see Guide for Applicants) and the NLnet submission form at nlnet.nl.

What the call funds and purpose

Restack is a cascade grant programme under the Open Internet Stack initiative (Horizon Europe identifier HORIZON-CL4) that aims to deliver, mature and scale open, deployable, scalable and secure internet commons across the technology stack. The programme targets foundational building blocks from open hardware (libre chips) and middleware to local-first infrastructure, open productivity tooling and user-facing applications that enable permissionless innovation and strengthen European digital autonomy. The Restack consortium (coordinated by NLnet Foundation) will competitively award a total programme budget of €7,000,000 in multiple small-to-medium R&D grants between 2026 and 2030.

Key programme facts:Opening date: 03 September 2026. Submission deadline for this call: 03 November 2026, 12:00 Brussels time. Total Restack budget: €7,000,000. Typical award size for first grants: €5,000 to €50,000, with possibility to scale in follow-up rounds. Expected project duration: 1–12 months (flexible). Call managed through NLnet's submission portal NLnet propose ¹.

Who can apply and applicant eligibility

Restack explicitly allows a wide range of applicant types. Anyone can apply, including private individuals and organisations of any type. The programme is designed to support independent researchers, individual developers, small teams and organisations developing open-source hardware or software and other commons. It accepts applications from non-profit organisations, SMEs, academic institutions, research institutes, startups, collectives without formal legal entity, and individuals, provided proposals have a clear European dimension and comply with the programme's English-language submission requirement and open licensing obligations.

1. 1Eligible applicant types: private individuals, collectives, associations (not-for-profit), SMEs, startups, universities, research institutes, NGOs, public benefit organisations and other organisation types except the Restack consortium partners and their paid staff.
2. 2Geographic eligibility: applicants should predominantly be from Horizon Europe-eligible countries (strong European dimension required).
3. 3Exclusions: the Restack consortium partners and their paid staff, and organisations financially invested in by NLnet where specified, are excluded from applying.

Funding modality and financial details

Funding is provided as grants (donations administered by NLnet Foundation) to third parties. The primary financial mechanism is cascade grants/sub-grants. The programme expects to award many small-to-medium grants; typical first-grant requests must be between €5,000 and €50,000. The guidance allows follow-up funding and larger grants: a first proposal may request up to €50,000; proposals larger than €50,000 must be preceded by successful smaller projects or equivalent prior work. Maximum amount per single proposal is €150,000. Maximum lifetime total per third party across the Restack programme is €500,000.

Funding range and limits:First-grant range: €5,000 to €50,000. Per-proposal maximum: €150,000. Cumulative maximum per third party for the programme lifetime: €500,000.

Scope of activities and technical priorities

Restack supports research and development activities that have a clear and direct contribution to the Open Internet Stack. Activities must be cost-effective and linked to Restack goals. All scientific outcomes must be open access and any novel software or hardware must be published under a recognised free and open source license in full. The call has a strict policy on AI: AI-generated proposals are not welcome in principle; if AI is used applicants must provide full prompt logs and mark generated content clearly.

1. 1In-scope activity examples: design and development of open source software and open hardware.
2. 2Validation, constructive inquiry, adaptation and software engineering to increase quality and new usage areas.
3. 3Formal security proofs, security audits, testing and CI design, and accessibility audits.
4. 4Documentation, educational materials and usability/inclusive design research.
5. 5Standardisation activities and standards body membership fees.
6. 6Measures to improve deployability (packaging, reproducible builds).
7. 7Scientific research and participation in community events (hackathons, IETF, W3C, RIPE, FOSDEM).
8. 8Project management and out-of-pocket infrastructure costs essential to project delivery.

Out-of-scope examples:general AI development unless it is already widely deployed (>€1 millionactive human users) and directly relevant to the stack. Proprietary-licensed outcomes are disallowed because of the FLOS license requirement.

Evaluation, scoring and selection procedure

The submission process is single-stage. Proposals must be concise (main application equivalent to no longer than two pages). The evaluation uses a two-stage review: an initial eligibility/knock-out check followed by scoring on three weighted criteria. Projects failing any hard eligibility criteria are rejected outright. Projects that pass receive numeric scores; projects scoring above the cut-off proceed to clarifying questions and possible revision in a second stage. Final selections are validated by an independent review committee.

Scoring scale:7-point scale. Minimum total weighted score to pass to the second stage: above 5.0 (out of 7). Selected projects are ranked by expected overall value to the Open Internet Stack and funding is allocated until budget is exhausted.

Application process and templates

Applications are submitted through NLnet's online form at nlnet.nl. The form asks for plain-English answers and expects concise, self-contained proposals. Attachments are optional (HTML, PDF, ODF, images, plain text) up to 50 MB in total. The submission form fields and guidance are reflected in NLnet's portal and include required sections and suggested length limits.

1. 1Which fund are you applying for (select Restack).
2. 2Project website(s) / repositories (optional).
3. 3Project summary and expected results (max 1000 characters).
4. 4Amount requested in Euros (first grants: €5,000–50,000).
5. 5Budget breakdown and justification.
6. 6Task list with time/effort estimates and applied rates.
7. 7Comparison with similar projects and differentiation (max 4000 characters).
8. 8Technical challenges (max 4000 characters).
9. 9Ecosystem engagement and main users (max 2000 characters).
10. 10Applicant CV and relevant experience (max 2000 characters).
11. 11Other funding sources (max 1000 characters).
12. 12Attachments (optional), and generative AI disclosure.

Applicants must provide an AI disclosure answer on the form and, if GenAI was used, a prompt provenance log as required by NLnet's Generative AI policy.

Consortium requirement and project structure

Single applicant projects are explicitly allowed. There is no mandatory requirement to form a consortium; small individual applicants, collectives without legal entity and small teams are welcome. Projects should nonetheless demonstrate a clear European dimension and sufficient capacity to carry out the planned R&D within the proposed duration and budget. Proposals may reference collaborations or dependencies on upstream projects and explain engagement with relevant upstream maintainers or communities.

Geographic and beneficiary scope

Beneficiary scope is primarily Horizon Europe-eligible countries. The call emphasizes a clear European dimension and expects applicants to be mostly from eligible European countries. Projects with relevant European impact and open licensing will be prioritised. For details on country eligibility consult the main Restack guidance and Horizon Europe eligibility rules.

Project maturity and expected project stages

Restack targets R&D across several maturity levels with emphasis on practical, deployable outcomes. Typical expected project stages include research, development, validation and demonstration leading to open-source deliverables; projects are short (1–12 months) and intended to yield implementable results or clear prototypes rather than long-term scale-up within one grant. Successful projects with proven potential may be invited to apply for follow-on funding to progress towards scale-up and wider deployment.

Co-funding, financial conditions and legal

There is no mandatory co-funding requirement stated for third parties; Restack determines grant amounts necessary to achieve key objectives and adjusts for ineligible costs. Grants are administered as donations by NLnet (a public benefit organisation) and enjoy beneficial tax conditions under charitable gift rules where applicable. Final grant amounts are formalised in a Memorandum of Understanding (MoU). Applicants can reject offered grant amounts prior to signing the MoU. Projects above €50,000 may be subject to independent security audits and payment can be conditional on audit outcomes.

Selection timeline and application stages

Submission model:single-stage submission with two-stage evaluation process (initial eligibility screening and scoring, followed by clarifying questions / revision and final validation). Practical application stages count as two main assessment stages plus the independent validation step. The overall application path therefore comprises: 1) submission and eligibility check, 2) scoring and shortlisting, 3) clarifying questions and possible revision, 4) final ranking and independent review committee validation, then 5) MoU negotiation and grant award.

How many decision stages?:Effectively 3 review stages in the selection pipeline: 1) eligibility/knock-out check, 2) scored technical review and potential clarifications/revision, 3) independent review committee validation before awarding.

Success rates and priorities

Restack does not publish an explicit numerical success rate for this specific call. Selection depends on the number and quality of applications and the remaining programme budget; projects must exceed a weighted score threshold (above 5.0/7.0) to proceed. Applicants should assume competitive selection and design proposals to maximise technical merit, strategic relevance to the Open Internet Stack and value for money.

Nature of support and non-financial services

Beneficiaries will receive monetary grants and may additionally receive non-financial support provided by the Restack consortium and NLnet, including technical assistance such as accessibility scans, security audits, reproducible packaging support, copyright and licensing guidance, governance and standardisation support, and opportunities for community engagement. These non-monetary supports are described as available to grantees to increase quality and deployability of outputs.

Mandatory open licensing and open access

All scientific outcomes must be published open access. Any novel software or hardware created under Restack must be published under a recognised free and open source license in its entirety. Deliverables must be fully available and satisfy accessibility best practices (e.g., WCAG for relevant outputs) where applicable. Failure to comply with open licensing or publication requirements can impact eligibility for follow-on funding.

AI and Generative AI policy

Restack/NLnet has an explicit Generative AI policy. In principle, AI-generated proposals are not welcome. If applicants used GenAI in the application process or project development they must disclose usage, provide prompt provenance logs, and mark generated content. Grantees must ensure that outputs attributable to GenAI remain legally publishable under FLOS licences and that human accountability for results is clearly demonstrated. Non-compliance may lead to rejection or termination of funding.

Contact and additional resources

Primary submission portal and applicant guidance:NLnet propose page NLnet propose and the Restack main page and guide for applicants Restack guide for applicants. The EU Funding & Tenders Portal listing for this competitive call provides the official identifier and summary: HORIZON-CL4 (Open Internet Stack) and the Restack opportunity page on the EU portal EU opportunity.

Summary: What is this opportunity about and why apply

Restack offers short, pragmatic, low-threshold R&D grants to individuals and small teams working on free/open-source building blocks needed to construct a resilient Open Internet Stack. It prioritises projects that contribute concrete, interoperable, deployable and trustworthy open-source software or hardware that reduce vendor lock-in, improve infrastructure decoupling, strengthen security and reproducibility, and support standards and accessibility. The programme provides cash grants combined with practical technical support (security audits, accessibility reviews, packaging and standardisation assistance) and opportunities for follow-on funding for successful projects. Applicants must provide concise proposals in English, comply with open licensing and open access rules, and demonstrate technical merit, strategic relevance to the Open Internet Stack, and good value for money. Projects are evaluated on a 7-point scale against weighted criteria and must surpass a minimum score to be considered for funding. Restack is intended to rapidly seed and mature a broad set of open internet commons that European public administrations, industry and civil society can adopt to improve strategic autonomy and digital resilience.

Footnotes

1. 1Submit proposals and find detailed applicant guidance at NLnet's proposal portal: nlnet.nl and read the Restack guide for applicants at nlnet.nl.

Restack is a cascade funding call under the Open Internet Stack initiative that supports small to medium sized research and development grants for open source and open hardware building blocks for a resilient open internet stack, and the current call is open from 03 September 2026 to 03 November 2026 at 12:00 Brussels time.[1][3]

What the funding supports

The programme aims to mature and scale new internet commons across the technology stack, including libre chips, middleware, productivity tools, local first infrastructure, end user applications, and other components that strengthen trust, interoperability, resilience, and strategic autonomy.[1][3]

Funding amount and duration

The broader Restack programme runs from 01 June 2026 to 30 May 2030, and new calls continue until the budget is allocated, which the guide expects to happen early in 2027.[6]

Who can apply

The call is open to anyone, including private individuals and organisations of any type, and the broader programme materials also describe eligible participants as SMEs, academics, public sector bodies, non-profits, communities, and individuals.[3][4]

What kinds of projects are in scope

• Design and development of open source software and open hardware.[1][3]
• Validation or constructive inquiry into existing or novel technical solutions.[1][3]
• Software engineering aimed at adapting to new usage areas or improving software quality.[1][3]
• Formal security proofs, security audits, testing, and continuous integration design.[1][3]
• Documentation for researchers, developers, and end users, including educational materials.[1][3]
• Standardisation activities, including membership fees of standards bodies.[1][3]
• Understanding user requirements and improving usability and inclusive design.[1][3]
• Necessary measures supporting deployability, such as packaging.[1][3]
• Scientific research and participation in technical or community events such as hackathons, IETF, W3C, RIPE meetings, and FOSDEM.[1][3]
• Project management and out of pocket infrastructure costs essential to delivery.[1][3]

AI related projects are generally out of scope unless they are already widely used throughout society and directly relevant to the stack, which is separate from the call's strict proposal policy on AI use.[1]

Core eligibility and output requirements

Proposals must fit the Open Internet Stack theme, have research and development as their primary objective, present a clear European dimension, and be complete and concise, with the main application limited to roughly two pages.[1][4]

All scientific outcomes must be published open access, and any novel software or hardware must be released in full under a recognised free and open source licence.[1][3]

Evaluation and selection

Applications are scored on a seven point scale using technical merit at 30 percent, strategic relevance to the Open Internet Stack and the goals of Restack at 40 percent, and overall value for money at 30 percent.[1]

Projects need a total weighted score above 5.0 out of 7 to be selected, and the call specifically values breakthrough contributions, interoperability, redundant implementation through norms and standards, and progress in infrastructure layers, service management, deployment innovation, and client side services.[1]

Application process and conditions

Applications are submitted through the NLnet proposal form, and applicants are advised to read the call page and guide before drafting a proposal¹.[1][4][6]

Grants are not paid upfront but are divided into milestones with amounts assigned to each milestone.[4][6]

The expected review and award process takes about three to five months after the deadline, and facilities and administrative costs are generally not eligible unless exceptional circumstances apply.[4][6]

The programme has a strict AI policy:AI generated proposals are generally not welcome, any submission involving AI requires a full prompt log, and any generated content must be clearly marked as such.[1][4]

Practical applicant takeaways

1. 1Build around a concrete open internet stack contribution that improves trust, security, interoperability, or deployability.[1][3]
2. 2Keep the proposal short, technically clear, and European in scope, with a realistic work plan and budget.[1][4]
3. 3Use open access publication and recognised free or open source licensing from the start because these are mandatory outputs.[1][3]
4. 4If the project could scale later, present the initial request as a focused proof of impact with a credible follow on pathway.[1][6]

Footnotes

1. 1Official programme information is available on the EU Funding and Tenders Portal EU Funding and Tenders Portal and on the Restack call page Restack.[1][6]