Arc vs Flow Engineering: Requirements and Verification for Space Teams

For fast-moving space teams, we recommend starting with Arc. Arc links requirements to systems, interfaces, risks and verification records. Engineers propose requirement changes on branches, inspect the differences, record review decisions and merge approved work into the baseline. Test results and evidence remain linked to the requirements and configurations they verify.

Flow Engineering is a credible alternative with a hardware systems graph connecting requirements, design artefacts and tests. Both products support branching, review and AI assistance. Evaluate Arc by taking one requirement from a proposed change through review to its linked test evidence. The shared payload example below gives you the records and decisions to use in that evaluation.

Jump to the comparison table, the shared evaluation, pricing and trials or questions and answers.

Why choose Arc for your space programme?

Arc gives systems and test engineers three concrete ways to manage a changing design:

• Follow a requirement to the records it affects. Arc maintains links in both directions between requirements, systems, interfaces and verification records. Arc shows trace paths, coverage and gaps for change reviews. Engineers maintain the relationships and assess the engineering dependencies.
• Review a proposal before changing the baseline. Engineers create a branch, edit records, inspect differences and discuss the proposal before merge. Arc records the reviewer’s identity, decision, timestamp and reviewed material.
• Check which evidence supports each requirement. Arc stores verification methods, test plans, executions, results and evidence linked to requirements and configurations. Arc shows coverage and execution status. Engineers decide whether an existing result still supports the changed design.

Choosing your first dedicated tool: start with Arc when payload, bus and test engineers need to work from connected requirements and evidence. Begin with one work package, a proposed change and a review, then use the results to plan adoption across the team.

Replacing an existing tool: make Arc’s connected workflow for change and verification the centre of the evaluation. Bring a requirement whose impact is difficult to reconstruct in your current setup, then assess its relationships, review history and applicable evidence in Arc. Agree the migration and export requirements before moving the authoritative baseline.

When Flow Engineering belongs on the shortlist: its hardware-wide systems graph and cross-tool agents are relevant if your evaluation centres on connecting design tools. Its catalogue describes Excel, Jira, GitHub and Onshape connections, and its Basic plan targets smaller teams starting a first project. If your existing Flow setup already meets the programme’s needs, established integrations and retained history are practical reasons to stay.

Fit the tool to your contractual obligations: Arc records authenticated, attributable approvals. A contract requiring regulated electronic signatures needs separate validation of that requirement. If a customer mandates another authoritative system, retain that baseline and define how Arc exchanges records with it. A stable, single-owner requirements sheet remains an option for a small scope.

Compare the requirements-to-verification workflow

The Arc column states product capabilities. Flow Engineering entries use its first-party sources checked on 1 October 2026. Pricing and deployment terms apply to the package you select. On a narrow screen, scroll the table horizontally.

A shared evaluation: change one payload power interface

Fictional example, not a completed test of either product. Use a small 6U spacecraft work package. Baseline B1 permits an 18 W payload in imaging mode. A proposal raises that limit to 24 W. Other loads total 36 W and available peak supply is 59 W, so the illustrative margin changes from +5 W to −1 W. This arithmetic identifies a question for engineers. It does not prove the complete power design or decide which tests to repeat.

Supply B1, the source specification, the proposed change and a few illustrative results with hardware and procedure revisions. Link the first three verification items, but deliberately leave the thermal relationship incomplete. The purpose is to see whether a reviewer can distinguish known linked consequences from a possible engineering dependency that the model does not yet capture.

1. Preserve identity and meaning. Import or create the same IDs, units, owners and relationship types in each tool. Reconcile counts and inspect individual records. Keep the original source references.
2. Isolate the proposal. Change PAY-PWR-014 on a branch or the demonstrated controlled-change route. Confirm B1 is still the accepted state, and show the exact text, field and relationship differences.
3. Inspect consequences and uncertainty. Find AN-PWR-01, TEST-PWR-02 and TEST-IF-03 through explicit links. Ask whether the missing thermal link is visible, inferred or simply unknown. A clean coverage indicator must not be treated as proof that all physical dependencies have been modelled.
4. Make the engineering disposition. A named systems reviewer, payload owner and test engineer decide what to revise, inspect or reverify. Record the rationale, unresolved margin and missing thermal context. Do not accept an AI suggestion as verification closure.
5. Keep evidence applicable. Inspect the old result’s requirement revision, test article, procedure and configuration. Demonstrate whether it remains valid, needs review or is superseded, while preserving its history.
6. Review, approve and export. Show permissions, rejection and approval, then merge only the authorised change. Export the resulting records, relationships, decisions and evidence references. Have someone outside the demonstration reconstruct the B1-to-B2 decision from the package.

This is the workflow to explore in Arc: follow a requirement change through its linked context, control the review and keep the verification decision attached to the relevant configuration. Record each outcome as demonstrated, partly demonstrated or unresolved, then use the same criteria with Flow. The change-impact guide develops the review method further.

Migration: moving from spreadsheets or replacing a tool

Arc imports requirements from CSV, Word, Jira, Git and Confluence. It exports PDF, Excel, Word, PowerPoint, Markdown (.md), ReqIF, CSV and plain text (.txt).

From spreadsheets: identify the authoritative workbook and source records. Map IDs, hierarchy, fields, units, relationship semantics and evidence references. Separate cell values from formulas, comments, macros, attachments and review decisions. A CSV route cannot by itself preserve the behaviour of an Excel workbook. Use the Excel migration guide for mapping and reconciliation.

From another dedicated system: Arc preserves requirement IDs, relationships, attachments, baselines and historical review and approval records during import and export. Inventory these records in the source system, map their fields and reconcile the transferred records before cutover. Flow’s documented ReqIF import route covers import into Flow. It does not establish what a Flow export contains or demonstrate a Flow-to-Arc transfer.

Start your Arc evaluation with one work package: keep the source authoritative while reconciling a representative sample. Include missing links and awkward records, then take a proposed change through review and verification. This gives your team a concrete basis for planning adoption. Agree acceptance, rollback and record ownership before cutover. Migration scope and timing depend on the source material and agreed mapping.

Flow Engineering pricing and Arc evaluation access

On 1 October 2026, Flow Engineering’s public pricing page listed:

• Basic: $150 USD per editor per month. 500 requirements, one project and one configuration in the comparison matrix. API, integrations and test cases/plans are listed, with a “Try for free” route.
• Pro: $300 USD per editor per month. 5,000 requirements, five projects and unlimited configurations in the matrix, with priority support and viewer licences available.
• Enterprise: custom pricing. The matrix lists unlimited requirements and projects, SSO/SAML and GovCloud availability. Obtain the proposed package and deployment terms.

These are displayed list prices, not a quote. The reviewed page does not establish your billing commitment, taxes, negotiated price, minimum seats, viewer charges, AI usage allowance or trial duration and feature scope. Confirm those points directly with Flow. “All integrations” in a plan does not turn a catalogue entry marked “Coming Soon” into a delivered connection.

Start with a free Arc trial request. Enter your email in the trial request form and Luc will contact you to arrange setup. Arc does not publish paid prices or a fixed trial duration. Ask for the price, access date, trial scope and included support for your team.

For both products, cost the same number of editors and reviewers, required deployment, integration work, migration, training and ongoing administration. Then use the same work package to assess whether the proposed setup meets your acceptance criteria.

Verify integrations, AI processing and the deployment boundary

Arc’s REST API lets an authorised integration read programme records, create a working branch, preview edits and apply record or relationship changes. Custom integrations need field mappings, source identifiers and permissions for each connected tool. Programme tokens remain bound to the programme and the owner’s permissions. Baseline updates go through the review and merge workflow.

Flow’s current catalogue describes Excel, GitHub, Jira, Onshape and Python connections, while entries including Ansys, Epsilon 3, Matlab and SolidWorks are labelled “Coming Soon”. For either product, test the exact connection you need: what it reads or writes, how it identifies source revisions and what happens when an update fails.

Arc and its enabled model providers do not use customer content to train models. Arc gives administrators visibility of the active provider, model and processing boundary, plus controls for approved model endpoints. On-premises deployments support local inference. Air-gapped deployments run without required external calls and use offline updates. Provider retention follows the selected terms and configuration.

Flow Engineering also publishes a no-training policy and describes private inference, AI audit trails and self-hosted deployment. For both products, obtain the provider, inference location, subprocessors, retention periods and audit exports for the proposed deployment. Check those against your contract and data-handling requirements. No training does not mean zero retention or establish programme compliance.

In Arc, named reviewers record decisions against the material under review, while agents check records and propose work within their assigned permissions. Test the permissions of an author, reviewer and agent using the same proposed change. Flow’s merge documentation describes an administrator review bypass with a recorded reason and blocker snapshot. Inspect who can use it and how your process governs it. In either tool, engineers remain responsible for deciding whether the physical design and verification evidence are sufficient.

When another approach belongs on the shortlist

Retain a controlled spreadsheet or document for a small, stable scope with clear ownership and manageable evidence. Consider another modern requirements tool if its demonstrated review or document workflow better matches your team. Retain a customer-mandated enterprise environment when the contract, qualified history or required exchange governs the choice. A contained evaluation can coexist with that authority without replacing it.

The broader aerospace and space buyer guide covers twelve approaches and their decision boundaries. The space-startup shortlist narrows the choice around the next programme milestone. Use those guides for multi-vendor selection, and this page for the Arc and Flow Engineering workflow comparison.

Questions about Arc and Flow Engineering

How do Arc and Flow Engineering differ?

Arc links requirements to systems, interfaces and verification records. Engineers propose changes on a branch, inspect record-level differences and record review decisions before merging into the baseline. Test results and evidence stay linked to the requirements and configurations they verify. We recommend starting with Arc when those are the tasks your space team needs to manage. Flow Engineering describes a hardware-wide systems graph with agents connecting requirements, design and test tools. Both support connected records, branching, review and AI assistance, so use the same programme example to assess the fit.

Is Flow Engineering suitable for space teams?

Flow Engineering is a relevant candidate for space teams: its public product covers requirements, systems, interfaces and tests, and it publishes aerospace deployment and security information. Suitability for a particular programme still depends on its contractual outputs, selected plan, data boundary, review rules and verified integrations.

Does Flow Engineering offer a free trial?

On 1 October 2026, Flow Engineering’s pricing page linked a free trial from Basic, listed at $150 USD per editor per month. Pro was listed at $300 USD per editor per month and Enterprise at custom pricing. Confirm current billing terms, trial duration, enabled features and data handling directly with Flow.

What should we compare before moving from Excel?

Use the same requirement IDs, hierarchy, relationship types, proposed change and verification records in both tools. Reconcile imported fields and links, check a missing relationship, complete a review and inspect the export. CSV support or a spreadsheet integration does not establish preservation of an entire Excel workbook, including formulas, comments and attachments.

Can we migrate existing requirements and review history?

Yes. Arc preserves requirement IDs, relationships, attachments, baselines and historical review and approval records during import and export. Arc exports PDF, Excel, Word, PowerPoint, Markdown, ReqIF, CSV and plain text. Map the source fields and reconcile the transferred records before cutover. This comparison has not tested a Flow-to-Arc transfer, so the available Flow export still needs to be checked against the records you intend to move.

What must we verify about AI and sensitive programme data?

Arc and its enabled model providers do not use customer content to train models. Arc administrators identify the active provider, model and processing boundary, and configure agent permissions. Engineers approve controlled changes. For either vendor, check inference location, provider retention, audit retention and permitted write actions for the selected deployment. No training does not mean zero retention or establish programme compliance.

Sources and review method

Flow Engineering sources checked on 1 October 2026: its product homepage, pricing, integration catalogue, security information and API documentation, including the specific endpoints discussed above. Arc references: product guide, the capability references linked throughout this comparison and security and deployment guide. Arc’s import, export and record-preservation capabilities were confirmed by its co-founder on 2 October 2026. Recheck vendor prices and contract terms before procurement.

This article is part of Arc’s requirements management software comparison library, where every shortlisted approach is assessed with the same programme-level criteria.

Evaluate Arc

See your next engineering change in Arc

Request a free Arc trial. Use the payload example above to link requirements to verification records, propose a change on a branch, inspect the differences and record a review decision before merging.

Luc will email from luc@archelps.com to arrange setup. Agree trial scope and data handling before adding programme information.

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