Wireframing is the cheapest phase of design and the one people most often over-tool. What you are paying for as prices rise is almost never drawing ability — it is collaboration, reusable components and handoff.
Excalidraw costs nothing, needs no account, and saves to a local .excalidraw file that is plain JSON — so it can live in your repository next to the code it describes, and it diffs. The deliberately hand-drawn look is a feature at this stage: nobody argues about a corner radius on a sketch. tldraw is similar with a slightly more polished feel.
Penpot is free and open source with no editor limit, which is the important distinction from every commercial free tier. It covers real component work and prototyping, and it can be self-hosted with Docker if data residency is a constraint. Figma's free tier allows a limited number of files and editors and unlimited viewers, which is often sufficient for a solo project.
Also underrated: paper and a phone camera. For flow-level thinking it is faster than any tool and the throwaway quality is honest.
Moving to a paid seat in a commercial tool typically unlocks unlimited files, version history beyond 30 days, shared libraries, and permission controls. In practice the two that matter are shared libraries — so a component defined once is available in every file — and version history, which is what saves you when a file is wrecked at 6pm. Pricing is per editor per month with an annual discount, and viewers are usually free, so the number to budget is how many people actually edit, which is nearly always smaller than the team.
Design system enforcement, branching and merging of design files, SSO, audit logs, and dev handoff features. These are organisational controls rather than design capability. If you are three people, they are money spent on problems you do not have. If you are thirty and shipping a design system, the version-control and library-management features are the cheapest part of the operation.
Solo, wireframing only: Excalidraw, free, done. Small team wanting components and shared libraries without per-seat cost: Penpot. Team where engineers need structured handoff and the wider company already uses it: a commercial tool at the standard tier — the integration and familiarity are worth more than the feature list. Large organisation with a real design system: the enterprise tier, because you are buying governance.
Whether the wireframe answers a question. A wireframe that settles what goes on the screen and in what order has done its job at any price, including zero. Time spent making it look finished is time spent on the wrong phase — and the tool that lets you produce something ugly quickly is more valuable at this stage than the one that makes it beautiful slowly.