Emlid Flow Alternatives: Free and Open Options for Reach Owners

Emlid's Reach receivers are one of the most popular ways to get centimeter-grade RTK without a five-figure budget, and Emlid Flow is the app they were designed to pair with. If you own a Reach, Flow is a reasonable default. But it is not the only app that can talk to your receiver, and depending on what you need, another option (or a mix of options) may fit better. Here is an honest look at the landscape as of mid-2026.

What Emlid Flow's free tier actually gives you

Credit where it is due: Flow's free tier is genuinely capable. Without paying anything you get receiver setup and firmware management, an NTRIP client for corrections, point collection, stakeout, exports to CSV, DXF, SHP, and KML, and projects shared with up to 10 team members. For a lot of point-based fieldwork, that covers the whole job. If your workflow is "connect to corrections, collect points, stake points, export a CSV," the free tier does it.

What Emlid Flow Pro adds, and what it costs

Flow Pro is $240 per user per year (or $24.99 monthly) as of mid-2026, per Emlid's pricing pages. The subscription unlocks the features that turn a point collector into a fuller survey tool:

• Linework and code libraries, so field coding builds lines and polygons as you shoot
• CAD and DTM support for background drawings and surfaces
• Localization (site calibration) to tie GNSS to a local grid
• COGO tools and survey reports

Whether that is worth it depends on your work. If you localize to plat coordinates weekly or code linework on every job, $240/yr may be an easy call. If you need those features twice a year, it can feel like a lot for a receiver you already paid roughly $2,400 for (Reach RX2 is $2,399; RS4 Pro is $4,599 as of mid-2026). That price gap is why many Reach owners go looking for alternatives.

The alternatives, honestly compared

Any app that accepts Bluetooth NMEA input can use a Reach as its position source. The main candidates:

SW Maps (free, closed source)

SW Maps is free and widely used in the RTK hobbyist and low-cost mapping world. It includes an NTRIP client and connects to Bluetooth NMEA receivers, so a Reach works fine. It is GIS-flavored rather than survey-flavored, and it is closed-source freeware, so you are relying on the goodwill of a single developer rather than an open codebase. Still, for free point and feature collection it is hard to argue with.

QField and Mergin Maps (open source, QGIS-first)

QField (GPL) and Mergin Maps (GPL/AGPL) are the two big open-source field apps, both built around QGIS. They are mature, actively developed, and genuinely open. The catch for surveyors is the workflow direction: both assume you design a project in desktop QGIS first, then push it to the field device. That is a natural fit for GIS teams and a less natural one for a surveyor who wants to open an app, connect a rover, and start shooting points against a coordinate system and code list. They are field GIS tools first, survey tools second.

The gap: no open-source survey-first app, yet

Notice the pattern. The free options are either closed source (SW Maps, Flow's free tier) or open source but GIS-first (QField, Mergin Maps). As of mid-2026 there is no open-source app built around the surveyor's workflow: codes that draw linework, stakeout, site calibration, COGO, and PNEZD-style exports, starting on the phone rather than on a desktop.

That gap is what Open Survey is being built to fill. It is in development, not shipped, so treat this as a roadmap rather than a review: a free, open-source iPhone and iPad app that works with any Bluetooth NMEA receiver (with first-class Emlid Reach support), includes an NTRIP client, and plans to ship linework, code libraries, localization, COGO, DXF import/export, and reports free rather than behind a subscription. Every shot records fix type, H/V RMS, PDOP, satellite count, and correction age, which matters for QA (see our NMEA GGA and GST explainer for why).

How to choose

• You mostly collect and stake points: Flow's free tier already does this well. No reason to switch.
• You need linework, localization, or COGO regularly: Flow Pro is the polished, supported path today. Budget the $240/user/yr and compare it against your billable time.
• Your organization lives in QGIS: QField or Mergin Maps will slot into your existing desktop workflow and cost nothing.
• You want free, simple field collection and do not mind closed source: SW Maps is a solid utility player.
• You want survey-first and open source: that category is still being built. Open Survey is our attempt at it.

Whatever app you choose, the fundamentals stay the same. If you are new to RTK, start with what RTK GNSS surveying actually is, then read up on site calibration and the PNEZD point file format, because those concepts transfer between every app on this list.