diff --git a/Project.toml b/Project.toml
index 87fc21e43..90336dc02 100644
--- a/Project.toml
+++ b/Project.toml
@@ -33,6 +33,7 @@ QuadGK = "1fd47b50-473d-5c70-9696-f719f8f3bcdc"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 SpatialIndexing = "d4ead438-fe20-5cc5-a293-4fd39a41b74c"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
+TestItemRunner = "f8b46487-2199-4994-9208-9a1283c18c0a"
 ThreadSafeDicts = "4239201d-c60e-5e0a-9702-85d713665ba7"
 UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
diff --git a/src/schematics/SchematicDrivenLayout.jl b/src/schematics/SchematicDrivenLayout.jl
index 18259d909..af43b43ec 100644
--- a/src/schematics/SchematicDrivenLayout.jl
+++ b/src/schematics/SchematicDrivenLayout.jl
@@ -110,6 +110,7 @@ export @component,
     replace_component!,
     route!,
     set_parameters
+export extract_parameters, parameters_to_yaml
 export ProcessTechnology, SimulationTarget, ArtworkTarget, SolidModelTarget
 export base_variant, flipchip!, map_metadata!, @composite_variant, @variant
 
@@ -137,6 +138,8 @@ include("components/variants.jl")
 include("solidmodels.jl")
 include("pdktools.jl")
 
+include("parameter_extraction.jl")
+
 include("ExamplePDK/ExamplePDK.jl")
 
 end # module
diff --git a/src/schematics/parameter_extraction.jl b/src/schematics/parameter_extraction.jl
new file mode 100644
index 000000000..e84d96347
--- /dev/null
+++ b/src/schematics/parameter_extraction.jl
@@ -0,0 +1,177 @@
+"""
+    extract_parameters(schematic::Schematic) -> Dict
+    extract_parameters(g::SchematicGraph) -> Dict
+
+Walk the component hierarchy and return a dictionary with two top-level keys:
+- `:defaults` — maps each component type name to its `default_parameters`
+- `:components` — maps each node id to its parameters, with nested `:subcomponents`
+"""
+function extract_parameters(sch::Schematic)
+    return extract_parameters(sch.graph)
+end
+
+function extract_parameters(g::SchematicGraph)
+    defaults = Dict{String,Any}()
+    components_dict = Dict{String,Any}()
+
+    for node in nodes(g)
+        comp = component(node)
+        _collect_defaults!(defaults, comp)
+        components_dict[node.id] = _extract_node(comp, defaults)
+    end
+
+    return Dict("defaults" => defaults, "components" => components_dict)
+end
+
+function _collect_defaults!(defaults::Dict, comp::AbstractComponent)
+    type_name = string(nameof(typeof(comp)))
+    if !haskey(defaults, type_name)
+        defaults[type_name] = _params_to_dict(default_parameters(typeof(comp)))
+    end
+    if comp isa AbstractCompositeComponent
+        for sub_comp in components(comp)
+            _collect_defaults!(defaults, sub_comp)
+        end
+    end
+end
+
+function _extract_node(comp::AbstractComponent, defaults::Dict)
+    type_name = string(nameof(typeof(comp)))
+    entry = Dict{String,Any}(
+        "type" => type_name,
+        "parameters" => _params_to_dict(non_default_parameters(comp))
+    )
+    if comp isa AbstractCompositeComponent
+        subs = Dict{String,Any}()
+        for sub_node in nodes(graph(comp))
+            sub_comp = component(sub_node)
+            subs[sub_node.id] = _extract_node(sub_comp, defaults)
+        end
+        if !isempty(subs)
+            entry["subcomponents"] = subs
+        end
+    end
+    return entry
+end
+
+function _params_to_dict(params::NamedTuple)
+    d = Dict{String,Any}()
+    for (k, v) in pairs(params)
+        k === :name && continue
+        d[string(k)] = _format_value(v)
+    end
+    return d
+end
+
+function _format_value(v)
+    if v isa Unitful.Quantity
+        return string(v)
+    elseif v isa AbstractComponent
+        return string(nameof(typeof(v)))
+    elseif v isa Tuple
+        return [_format_value(x) for x in v]
+    elseif v isa AbstractArray
+        return [_format_value(x) for x in v]
+    elseif v isa NamedTuple
+        return _params_to_dict(v)
+    else
+        return v
+    end
+end
+
+# --- YAML serialization ---
+
+"""
+    parameters_to_yaml(schematic; io=stdout)
+    parameters_to_yaml(g::SchematicGraph; io=stdout)
+
+Extract parameters from a schematic and write YAML with anchored defaults
+and merge-key-based component instances.
+"""
+function parameters_to_yaml(sch::Schematic; io::IO=stdout)
+    return parameters_to_yaml(sch.graph; io=io)
+end
+
+function parameters_to_yaml(g::SchematicGraph; io::IO=stdout)
+    data = extract_parameters(g)
+    _write_yaml(io, data)
+end
+
+function parameters_to_yaml(sch_or_graph, filename::AbstractString)
+    open(filename, "w") do io
+        parameters_to_yaml(sch_or_graph; io=io)
+    end
+end
+
+function _write_yaml(io::IO, data::Dict)
+    defaults = data["defaults"]
+    comps = data["components"]
+
+    println(io, "components:")
+
+    println(io, "  default_parameters:")
+    for (type_name, params) in sort(collect(defaults); by=first)
+        anchor = _anchor_name(type_name)
+        println(io, "    $type_name: &$anchor")
+        _write_yaml_dict(io, params, 6)
+    end
+
+    println(io)
+    for (node_id, entry) in sort(collect(comps); by=first)
+        println(io, "  $node_id:")
+        _write_component_entry(io, entry, 4)
+    end
+end
+
+function _write_component_entry(io::IO, entry::Dict, indent::Int)
+    prefix = " " ^ indent
+    type_name = entry["type"]
+    anchor = _anchor_name(type_name)
+
+    println(io, prefix, "type: ", type_name)
+    println(io, prefix, "<<: *", anchor)
+
+    params = entry["parameters"]
+    if !isempty(params)
+        for (k, v) in sort(collect(params); by=first)
+            println(io, prefix, k, ": ", _yaml_value(v))
+        end
+    end
+
+    if haskey(entry, "subcomponents")
+        println(io, prefix, "subcomponents:")
+        for (sub_id, sub_entry) in sort(collect(entry["subcomponents"]); by=first)
+            println(io, prefix, "  ", sub_id, ":")
+            _write_component_entry(io, sub_entry, indent + 4)
+        end
+    end
+end
+
+function _write_yaml_dict(io::IO, d::Dict, indent::Int)
+    prefix = " " ^ indent
+    for (k, v) in sort(collect(d); by=first)
+        println(io, prefix, k, ": ", _yaml_value(v))
+    end
+end
+
+function _yaml_value(v)
+    if v isa AbstractString
+        needs_quoting = occursin(r"[:#\[\]{}&*!|>'\",]", v) || v in ("true", "false", "null", "yes", "no")
+        return needs_quoting ? "\"$(escape_string(v))\"" : v
+    elseif v isa Bool
+        return v ? "true" : "false"
+    elseif v isa Number
+        return string(v)
+    elseif v isa AbstractVector
+        return "[" * join((_yaml_value(x) for x in v), ", ") * "]"
+    elseif v isa Dict
+        buf = IOBuffer()
+        println(buf)
+        _write_yaml_dict(buf, v, 0)
+        return String(take!(buf))
+    else
+        return repr(v)
+    end
+end
+
+_anchor_name(type_name::AbstractString) = type_name * "_defaults"
diff --git a/test/test_parameter_extraction.jl b/test/test_parameter_extraction.jl
new file mode 100644
index 000000000..69e1270ed
--- /dev/null
+++ b/test/test_parameter_extraction.jl
@@ -0,0 +1,160 @@
+@testsnippet ParamExtractionSetup begin
+    using Test
+    using DeviceLayout, Unitful
+    import Unitful: nm, μm, mm
+    using DeviceLayout.SchematicDrivenLayout
+
+    import DeviceLayout.SchematicDrivenLayout:
+        AbstractComponent,
+        AbstractCompositeComponent,
+        nodes,
+        component,
+        extract_parameters,
+        parameters_to_yaml
+
+    reset_uniquename!()
+
+    @compdef struct ExtTestLeaf <: AbstractComponent{typeof(1.0nm)}
+        name::String = "example_leaf_component"
+        width = 100nm
+        gap = 10nm
+    end
+    SchematicDrivenLayout.hooks(::ExtTestLeaf) = (
+        origin=PointHook(Point(0nm, 0nm), 0),
+    )
+
+    @compdef struct ExtTestComposite <: CompositeComponent
+        name::String = "example_composite_component"
+        leaf_width = 100nm
+        leaf_gap = 10nm
+        spacing = 500nm
+    end
+    SchematicDrivenLayout.hooks(::ExtTestComposite) = (
+        origin=PointHook(Point(0nm, 0nm), 0),
+    )
+
+    function SchematicDrivenLayout._build_subcomponents(c::ExtTestComposite)
+        @component leaf_a = ExtTestLeaf begin
+            width = c.leaf_width
+            gap = c.leaf_gap
+        end
+        @component leaf_b = ExtTestLeaf begin
+            width = c.leaf_width
+        end
+        return (leaf_a, leaf_b)
+    end
+
+    function SchematicDrivenLayout._graph!(
+        g::SchematicGraph,
+        ::ExtTestComposite,
+        subcomps::NamedTuple
+    )
+        add_node!(g, subcomps.leaf_a)
+        add_node!(g, subcomps.leaf_b)
+        return nothing
+    end
+
+    SchematicDrivenLayout.map_hooks(::ExtTestComposite) =
+        Dict((1 => :origin) => :origin)
+
+    const tdir = mktempdir()
+    const save_yaml = get(ENV, "SAVE_YAML", "") == "1"
+    const yaml_outdir = joinpath(@__DIR__, "yaml_output")
+
+    function maybe_save_yaml(g::SchematicGraph, name::String)
+        save_yaml || return
+        mkpath(yaml_outdir)
+        outpath = joinpath(yaml_outdir, name * ".yaml")
+        parameters_to_yaml(g, outpath)
+        @info "Saved YAML to $outpath"
+    end
+end
+
+@testitem "extract_parameters basics" setup = [ParamExtractionSetup] begin
+    g = SchematicGraph("test_extraction")
+    leaf = ExtTestLeaf(width=200nm)
+    node = add_node!(g, leaf)
+
+    data = extract_parameters(g)
+
+    # Defaults section has the type
+    @test haskey(data["defaults"], "ExtTestLeaf")
+    defs = data["defaults"]["ExtTestLeaf"]
+    @test defs["width"] == string(100nm)
+    @test defs["gap"] == string(10nm)
+
+    # Instance only has overrides
+    entry = data["components"][node.id]
+    @test entry["type"] == "ExtTestLeaf"
+    @test entry["parameters"]["width"] == string(200nm)
+    @test !haskey(entry["parameters"], "gap")
+
+    maybe_save_yaml(g, "basics")
+end
+
+@testitem "extract_parameters composite hierarchy" setup = [ParamExtractionSetup] begin
+    g = SchematicGraph("test_composite")
+    comp = ExtTestComposite(leaf_width=300nm)
+    node = add_node!(g, comp)
+
+    data = extract_parameters(g)
+
+    # Both types should appear in defaults
+    @test haskey(data["defaults"], "ExtTestComposite")
+    @test haskey(data["defaults"], "ExtTestLeaf")
+
+    # Top-level instance has override
+    entry = data["components"][node.id]
+    @test entry["type"] == "ExtTestComposite"
+    @test entry["parameters"]["leaf_width"] == string(300nm)
+
+    # Subcomponents present
+    @test haskey(entry, "subcomponents")
+    @test length(entry["subcomponents"]) == 2
+
+    maybe_save_yaml(g, "composite_hierarchy")
+end
+
+@testitem "parameters_to_yaml output" setup = [ParamExtractionSetup] begin
+    g = SchematicGraph("test_yaml")
+    add_node!(g, ExtTestLeaf(width=200nm))
+    add_node!(g, ExtTestComposite(leaf_width=300nm, spacing=1000nm))
+
+    buf = IOBuffer()
+    parameters_to_yaml(g; io=buf)
+    yaml_str = String(take!(buf))
+
+    # Check structure
+    @test occursin("components:", yaml_str)
+    @test occursin("default_parameters:", yaml_str)
+
+    # Check anchors and merge keys
+    @test occursin("&ExtTestLeaf_defaults", yaml_str)
+    @test occursin("*ExtTestLeaf_defaults", yaml_str)
+    @test occursin("<<: *ExtTestLeaf_defaults", yaml_str)
+
+    # Check type field present
+    @test occursin("type: ExtTestLeaf", yaml_str)
+    @test occursin("type: ExtTestComposite", yaml_str)
+
+    # Check overrides show up
+    @test occursin(string(200nm), yaml_str)
+    @test occursin(string(300nm), yaml_str)
+
+    maybe_save_yaml(g, "yaml_output")
+end
+
+@testitem "parameters_to_yaml file output" setup = [ParamExtractionSetup] begin
+    g = SchematicGraph("test_yaml_file")
+    add_node!(g, ExtTestLeaf(width=500nm))
+
+    filepath = joinpath(tdir, "test_params.yaml")
+    parameters_to_yaml(g, filepath)
+
+    @test isfile(filepath)
+    content = read(filepath, String)
+    @test occursin("components:", content)
+    @test occursin("default_parameters:", content)
+
+    maybe_save_yaml(g, "file_output")
+end
diff --git a/test/yaml_output/basics.yaml b/test/yaml_output/basics.yaml
new file mode 100644
index 000000000..ff97840ef
--- /dev/null
+++ b/test/yaml_output/basics.yaml
@@ -0,0 +1,11 @@
+components:
+  default_parameters:
+    ExtTestLeaf: &ExtTestLeaf_defaults
+      gap: 10 nm
+      name: leaf
+      width: 100 nm
+
+  leaf:
+    type: ExtTestLeaf
+    <<: *ExtTestLeaf_defaults
+    width: 200 nm
diff --git a/test/yaml_output/composite_hierarchy.yaml b/test/yaml_output/composite_hierarchy.yaml
new file mode 100644
index 000000000..3a3db9323
--- /dev/null
+++ b/test/yaml_output/composite_hierarchy.yaml
@@ -0,0 +1,23 @@
+components:
+  default_parameters:
+    ExtTestComposite: &ExtTestComposite_defaults
+      leaf_gap: 10 nm
+      leaf_width: 100 nm
+      spacing: 500 nm
+    ExtTestLeaf: &ExtTestLeaf_defaults
+      gap: 10 nm
+      width: 100 nm
+
+  example_composite_component:
+    type: ExtTestComposite
+    <<: *ExtTestComposite_defaults
+    leaf_width: 300 nm
+    subcomponents:
+      leaf_a:
+        type: ExtTestLeaf
+        <<: *ExtTestLeaf_defaults
+        width: 300 nm
+      leaf_b:
+        type: ExtTestLeaf
+        <<: *ExtTestLeaf_defaults
+        width: 300 nm