Merge / Dissolve & Field Calculator

Append GeoJSON layers, union polygons (all or by attribute), and compute properties with expressions — fully in your browser.

No upload Combine by attribute Standards‑based
Tip: Use Scan Attributes to pick a dissolve field. In Field Calculator, reference properties as ${field_name} and use helpers like area(), length(), round(x,2).
Precision:
Layer A
Layer B (optional, for Merge)
Appends features from B into A (if provided). For more than two layers, run sequentially.
Optional summary fields (numeric):
Use comma‑separated field lists. Output columns are prefixed (e.g., sum_pop).
Syntax: reference properties as ${field}. Available functions: area(), length(), round(x,n), toNumber(x), toInt(x), upper(x), lower(x), concat(a,b,...), now(). Operators: + - * / %, comparisons == != > < >= <=, and ternary cond ? a : b.
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Result
No data yet.
Output: GeoJSON
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Notes:
  • Merge appends features; set _src tag to track origin.
  • Dissolve unions polygons (all or by property). Optional numeric summaries: sum/avg/min/max.
  • Field Calculator supports property tokens (${'{'}name{'}'}) and helper functions like area(), length(), round().