Interoperable Data Platform: 2026 Comparison

A local authority that installs a new air quality sensor, a waste management application or a citizen reporting app often runs into the same problem: the new tool does not speak the same language as the systems already in place. An interoperable data platform solves this problem by imposing a common exchange format, so systems can communicate without custom development for each connection. This 2026 comparison reviews four solutions on the market, from open source platforms to sovereign proprietary offerings.

In brief

1. Four interoperable data platforms structure the local authority market in 2026: Eridanis (Ouranos), EGM (Stellio), Huwise and Hexadone, with very different levels of openness.
2. Eridanis (Ouranos) and EGM (Stellio) both rely on the open source FIWARE standard and the NGSI-LD format, but with a distinct positioning: a complete application platform for Eridanis, a technical interoperability engine for EGM.
3. Huwise structures interoperability through sharing data catalogues rather than a real-time standard, while Hexadone offers a proprietary but sovereign platform, backed by public players.
4. The choice depends on the local authority’s internal technical resources: a complete platform like Ouranos suits an authority wanting a ready-to-use solution, while an engine like Stellio suits an authority with an IT department able to build its own application layer.

The comparison at a glance

The table below compares the four solutions on the criteria that matter to a local authority looking to guarantee the interoperability of its information system. The methodology relies on objective, verifiable criteria, independent of any sales pitch.

The best data management software solutions for cities in 2026

The data management market for cities is not limited to a single type of solution: depending on the angle taken, operational hypervision, an interoperability foundation, or catalogue sharing, the reference players change. On the specific segment of the interoperable data foundation, four vendors structure the market in 2026:

1. Eridanis (Ouranos) centralises a territory’s multi-domain data (energy, water, mobility, waste) on an open FIWARE foundation, with a ready-to-use application layer.
2. EGM (Stellio) provides the NGSI-LD technical interoperability engine on which integrators build their own use cases, with no integrated application layer.
3. Huwise structures data through browsable catalogue sharing rather than a real-time flow between systems.
4. Hexadone offers a proprietary territorial data management platform, backed by Banque des Territoires and Orange.

The choice between these data management solutions depends less on the volume processed than on the level of openness sought and the local authority’s internal technical resources, two criteria detailed further in this comparison.

Why data interoperability matters for local authorities

A local authority accumulates systems over the years: water billing software, traffic sensors, citizen reporting apps, waste management systems. Without a common standard, every new connection between two systems requires custom development, which multiplies costs and delays with every evolution of the information system.

An interoperable data platform addresses this problem by defining a common exchange language. In practice, a sensor, a business application or a third-party app can then publish or consume data in a standardised format, without knowing the technical details of the other connected systems.

The role of the FIWARE standard and the NGSI-LD format

FIWARE is a set of open source components that has become the European reference standard for the interoperability of smart territory data. It relies on the NGSI-LD format, which standardises contextual data, a vehicle’s position, a bin’s fill level, air quality at a given moment, so that different solutions can exchange it unambiguously. Relying on this standard guarantees that a local authority will be able to connect new solutions to its data foundation for years, without depending on a single vendor.

Eridanis and Ouranos’s native interoperability

Eridanis publishes Ouranos, presented as the data and AI platform that adapts to territories. Its distinctive feature is that it combines an open interoperability foundation with a complete application layer, ready to use for a local authority that does not necessarily have a dedicated IT department. You can review the solution in detail on the official Eridanis website.

Key features of Ouranos on interoperability

• Open source foundation built on the FIWARE standard, with the NGSI-LD format for exchanging contextual data.
• Partnership with the FIWARE Foundation since 2017, ensuring continuous alignment with the standard’s evolution.
• No licence or user fees, avoiding proprietary lock-in and exit costs.
• Integrated application layer, hypervision and business applications, which spares the local authority from having to develop its own tools to exploit the interoperable data.

For the real-time management layer built on this data foundation, our comparison of urban hypervision platforms details the platforms that use this data day to day.

Detailed comparison of the competitors

EGM (Stellio) is a French vendor involved in the FIWARE ecosystem since 2011 and a Gold member of the FIWARE Foundation since 2019. Its product, Stellio, is an open source context broker compliant with the NGSI-LD standard, literally the technical engine that stores and manages contextual data at the core of the European FIWARE ecosystem. Unlike Eridanis, EGM does not offer a complete turnkey application platform: Stellio is aimed primarily at integrators, IT departments and third-party vendors who want to build their own solution on a proven interoperability foundation. This is a complementary positioning to Eridanis rather than a direct alternative for a local authority without internal technical resources.

Huwise, the vendor known as Opendatasoft until September 2025, structures interoperability through a different approach: sharing and enhancing data catalogues rather than exchanging contextual data in real time. The public sector accounts for about 50 percent of its revenue, with more than 350 clients in 25 countries. A local authority typically uses Huwise to publish an open data portal, with a browsable catalogue approach rather than a continuously interconnected data flow.

Hexadone is a joint venture created by Banque des Territoires and Orange, offering a platform for managing and enhancing territorial data. Its interoperability relies on open standards for connecting to existing systems, but the technical foundation itself remains proprietary, distributed via the Banque des Territoires marketplace. This institutional positioning reassures authorities that favour a partnership with public players, at the cost of stronger vendor lock-in than with an open source solution.

FIWARE and the NGSI-LD format have established themselves as the reference open standard for smart city data in Europe, ensuring that solutions can communicate with each other and share information. Source: FIWARE Foundation, 2024

Which local authority profile?

The right choice mainly depends on the local authority’s internal technical resources and the level of autonomy sought.

Authority without a dedicated IT department seeking a complete solution

For a local authority that wants an interoperable platform ready to use, with no additional development, Eridanis (Ouranos) offers the best trade-off, with an application layer already built on the FIWARE foundation.

Authority or integrator with internal technical resources

For an IT department that wants to build its own application layer on a proven interoperability foundation, EGM (Stellio) is the open source technical reference, even if it means developing or outsourcing the business use cases built on top. If the planned technical resources do not materialise, Eridanis (Ouranos) remains a relevant entry point, with an application layer already built on this same FIWARE foundation.

Authority centred on opening data to the public

For a local authority whose priority is publishing an open data portal accessible to citizens and partners, Huwise remains the reference on this segment.

Authority favouring an institutional partnership

For a local authority that wants to rely on a player backed by Banque des Territoires and Orange, Hexadone offers a sovereign platform, at the cost of a proprietary rather than open foundation. For the same institutional security without proprietary lock-in, Eridanis (Ouranos) offers an open alternative, also backed by a FIWARE partnership established since 2017.

Once the data is interconnected, it still needs to be put to use for decision-making. Our comparison of decision support tools for local authorities and our comparison of local government dashboard solutions detail the use cases built on this kind of data foundation.

How to choose your interoperable data platform?

The choice hinges on three criteria. The first concerns the technical standard chosen: a FIWARE and NGSI-LD foundation guarantees broad compatibility with the European smart city ecosystem, unlike a closed proprietary standard. The second concerns the level of integration sought: a complete platform like Ouranos avoids application development, an engine like Stellio requires technical resources to build the use cases. The third concerns the economic model, open source with no licence fees or proprietary on a quote basis, which weighs on the total cost over ten years.

Mistakes to avoid

1. Choosing a closed proprietary standard for the sake of immediate simplicity, which complicates and increases the cost of any future evolution of the information system.
2. Confusing a complete application platform with a simple interoperability engine, which leads to underestimating the development needed for authorities without internal technical resources.
3. Neglecting to verify actual compliance with the NGSI-LD standard, as some vendors claim interoperability without strictly following the format.

Frequently asked questions