diff --git a/.gitignore b/.gitignore
index 462bd1f..b380ecf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 /.vscode/
 
 Manifest.toml
+Manifest-*.toml
 fixture.tar.gz
 fixture
 .CondaPkg
diff --git a/ChunkCodecCore/CHANGELOG.md b/ChunkCodecCore/CHANGELOG.md
index cb038c1..73f6143 100644
--- a/ChunkCodecCore/CHANGELOG.md
+++ b/ChunkCodecCore/CHANGELOG.md
@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
+### BREAKING `can_concatenate` is now a decoder method instead of a `Codec` method [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
+
 ### BREAKING the return type of `try_encode`, `try_decode`, and `try_resize_decode!` changed to a new `MaybeSize` type [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
 
 ## [v0.5.3](https://github.com/JuliaIO/ChunkCodecs.jl/tree/ChunkCodecCore-v0.5.3) - 2025-08-09
diff --git a/ChunkCodecCore/src/interface.jl b/ChunkCodecCore/src/interface.jl
index 5964ba0..25a89dc 100644
--- a/ChunkCodecCore/src/interface.jl
+++ b/ChunkCodecCore/src/interface.jl
@@ -100,17 +100,6 @@ Return the default decode options for the codec.
 """
 function decode_options end
 
-"""
-    can_concatenate(::Codec)::Bool
-
-Return `true` if the codec has concatenation transparency.
-
-If `true`, and some encoded data `a` and `b` decode to `x` and `y` respectively, then
-the concatenation of `a` and `b` will
-decode to the concatenation of `x` and `y`
-"""
-can_concatenate(::Codec) = false
-
 """
     decoded_size_range(e)::StepRange{Int64, Int64}
 
@@ -258,10 +247,22 @@ function try_resize_decode!(d, dst::AbstractVector{UInt8}, src::AbstractVector{U
     end
 end
 
+"""
+    can_concatenate(d)::Bool
+
+Return `true` if the decoder has concatenation transparency.
+
+If `true`, and some encoded data `a` and `b` decode to `x` and `y` respectively, then
+the concatenation of `a` and `b` will
+decode to the concatenation of `x` and `y`
+"""
+can_concatenate(::Any) = false
+
 # allow passing codec to decode
 try_find_decoded_size(c::Codec, src::AbstractVector{UInt8}) = try_find_decoded_size(decode_options(c), src)
 try_decode!(c::Codec, dst::AbstractVector{UInt8}, src::AbstractVector{UInt8}; kwargs...) = try_decode!(decode_options(c), dst, src; kwargs...)
 try_resize_decode!(c::Codec, dst::AbstractVector{UInt8}, src::AbstractVector{UInt8}, max_size::Int64; kwargs...) = try_resize_decode!(decode_options(c), dst, src, max_size; kwargs...)
+can_concatenate(c::Codec) = can_concatenate(decode_options(c))
 
 """
     check_contiguous(x::AbstractVector{UInt8})
diff --git a/ChunkCodecCore/src/noop.jl b/ChunkCodecCore/src/noop.jl
index 12bdba9..c11ad5b 100644
--- a/ChunkCodecCore/src/noop.jl
+++ b/ChunkCodecCore/src/noop.jl
@@ -9,7 +9,6 @@ Copies the input.
 See also [`NoopEncodeOptions`](@ref) and [`NoopDecodeOptions`](@ref)
 """
 struct NoopCodec <: Codec end
-can_concatenate(::NoopCodec) = true
 decode_options(::NoopCodec) = NoopDecodeOptions() # default decode options
 
 """
@@ -72,6 +71,8 @@ end
 
 is_thread_safe(::NoopDecodeOptions) = true
 
+can_concatenate(::NoopDecodeOptions) = true
+
 function try_find_decoded_size(::NoopDecodeOptions, src::AbstractVector{UInt8})::Int64
     length(src)
 end
diff --git a/ChunkCodecCore/src/types.jl b/ChunkCodecCore/src/types.jl
index 61f72b8..0453cf7 100644
--- a/ChunkCodecCore/src/types.jl
+++ b/ChunkCodecCore/src/types.jl
@@ -7,9 +7,6 @@ Properties are public for reading.
 
 Required methods for a type `T <: Codec` to implement:
 - `decode_options(::T)::DecodeOptions`
-
-Optional methods to implement:
-- `can_concatenate(::T)::Bool`: defaults to `false`.
 """
 abstract type Codec end
 
@@ -51,6 +48,7 @@ Required methods for a type `T <: DecodeOptions` to implement:
 
 Optional methods to implement:
 - `is_thread_safe(::T)::Bool`: defaults to `false`.
+- `can_concatenate(::T)::Bool`: defaults to `false`.
 - `try_resize_decode!(::T, dst::AbstractVector{UInt8}, src::AbstractVector{UInt8}, max_size::Int64; kwargs...)::MaybeSize`: defaults to using `try_decode!` and `try_find_decoded_size`
 """
 abstract type DecodeOptions end
\ No newline at end of file
diff --git a/ChunkCodecTests/CHANGELOG.md b/ChunkCodecTests/CHANGELOG.md
index 161704b..a202cee 100644
--- a/ChunkCodecTests/CHANGELOG.md
+++ b/ChunkCodecTests/CHANGELOG.md
@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
-- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
+- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72) [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
 - Added support for Julia 1.6 [#68](https://github.com/JuliaIO/ChunkCodecs.jl/pull/68)
 
 ## [v0.1.5](https://github.com/JuliaIO/ChunkCodecs.jl/tree/ChunkCodecTests-v0.1.5) - 2025-07-28
diff --git a/ChunkCodecTests/src/ChunkCodecTests.jl b/ChunkCodecTests/src/ChunkCodecTests.jl
index 086880a..642ae49 100644
--- a/ChunkCodecTests/src/ChunkCodecTests.jl
+++ b/ChunkCodecTests/src/ChunkCodecTests.jl
@@ -27,6 +27,7 @@ export test_codec, test_encoder_decoder, rand_test_data
 function test_codec(c::Codec, e::EncodeOptions, d::DecodeOptions; trials=100)
     @test decode_options(c) isa DecodeOptions
     @test can_concatenate(c) isa Bool
+    @test can_concatenate(d) isa Bool
     @test e.codec == c
     @test d.codec == c
     @test is_thread_safe(e) isa Bool
@@ -39,15 +40,6 @@ function test_codec(c::Codec, e::EncodeOptions, d::DecodeOptions; trials=100)
     @test typeof(d)(;NamedTuple{d_props}(getproperty.((d,), d_props))...) == d
 
     test_encoder_decoder(e, d; trials)
-
-    # can_concatenate tests
-    if can_concatenate(c)
-        srange = decoded_size_range(e)
-        a = rand(UInt8, 100*step(srange))
-        b = rand(UInt8, 200*step(srange))
-        @test decode(d, [encode(e, a); encode(e, b);]) == [a; b;]
-        @test decode(d, [encode(e, UInt8[]); encode(e, UInt8[]);]) == UInt8[]
-    end
 end
 
 function test_encoder_decoder(e, d; trials=100)
@@ -141,6 +133,15 @@ function test_encoder_decoder(e, d; trials=100)
 
         @test decode(d, encoded) == data
     end
+
+    # can_concatenate tests
+    if can_concatenate(d)
+        srange = decoded_size_range(e)
+        a = rand(UInt8, 100*step(srange))
+        b = rand(UInt8, 200*step(srange))
+        @test decode(d, [encode(e, a); encode(e, b);]) == [a; b;]
+        @test decode(d, [encode(e, UInt8[]); encode(e, UInt8[]);]) == UInt8[]
+    end
 end
 
 function rand_test_data(s::Int64)::Vector{UInt8}
diff --git a/LibBzip2/CHANGELOG.md b/LibBzip2/CHANGELOG.md
index 5b84864..9ff5b3a 100644
--- a/LibBzip2/CHANGELOG.md
+++ b/LibBzip2/CHANGELOG.md
@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
-- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
+- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72) [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
 - Added support for Julia 1.6 [#68](https://github.com/JuliaIO/ChunkCodecs.jl/pull/68)
 
 ## [v0.2.1](https://github.com/JuliaIO/ChunkCodecs.jl/tree/LibBzip2-v0.2.1) - 2025-07-28
diff --git a/LibBzip2/src/ChunkCodecLibBzip2.jl b/LibBzip2/src/ChunkCodecLibBzip2.jl
index 7e0e0b4..134cd02 100644
--- a/LibBzip2/src/ChunkCodecLibBzip2.jl
+++ b/LibBzip2/src/ChunkCodecLibBzip2.jl
@@ -50,8 +50,6 @@ struct BZ2Codec <: Codec
 end
 decode_options(::BZ2Codec) = BZ2DecodeOptions()
 
-can_concatenate(::BZ2Codec) = true
-
 include("encode.jl")
 include("decode.jl")
 
diff --git a/LibBzip2/src/decode.jl b/LibBzip2/src/decode.jl
index 69ff54c..75d4fc5 100644
--- a/LibBzip2/src/decode.jl
+++ b/LibBzip2/src/decode.jl
@@ -45,6 +45,7 @@ function BZ2DecodeOptions(;
     BZ2DecodeOptions(codec)
 end
 is_thread_safe(::BZ2DecodeOptions) = true
+can_concatenate(::BZ2DecodeOptions) = true
 
 function try_find_decoded_size(::BZ2DecodeOptions, src::AbstractVector{UInt8})::Nothing
     nothing
diff --git a/LibLz4/CHANGELOG.md b/LibLz4/CHANGELOG.md
index fe618fe..edb48e0 100644
--- a/LibLz4/CHANGELOG.md
+++ b/LibLz4/CHANGELOG.md
@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
-- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
+- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72) [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
 - Added support for Julia 1.6 [#68](https://github.com/JuliaIO/ChunkCodecs.jl/pull/68)
 
 ## [v0.2.2](https://github.com/JuliaIO/ChunkCodecs.jl/tree/LibLz4-v0.2.2) - 2025-07-28
diff --git a/LibLz4/src/ChunkCodecLibLz4.jl b/LibLz4/src/ChunkCodecLibLz4.jl
index 24d11a9..af7ed5d 100644
--- a/LibLz4/src/ChunkCodecLibLz4.jl
+++ b/LibLz4/src/ChunkCodecLibLz4.jl
@@ -65,7 +65,6 @@ See also [`LZ4FrameEncodeOptions`](@ref) and [`LZ4FrameDecodeOptions`](@ref)
 struct LZ4FrameCodec <: Codec
 end
 decode_options(::LZ4FrameCodec) = LZ4FrameDecodeOptions() # default decode options
-can_concatenate(::LZ4FrameCodec) = true
 
 """
     struct LZ4BlockCodec <: Codec
diff --git a/LibLz4/src/decode.jl b/LibLz4/src/decode.jl
index d950085..0c8abbe 100644
--- a/LibLz4/src/decode.jl
+++ b/LibLz4/src/decode.jl
@@ -43,6 +43,8 @@ end
 
 is_thread_safe(::LZ4FrameDecodeOptions) = true
 
+can_concatenate(::LZ4FrameDecodeOptions) = true
+
 function try_find_decoded_size(::LZ4FrameDecodeOptions, src::AbstractVector{UInt8})::Nothing
     # TODO This might be possible to do using a method similar to ZstdDecodeOptions
     # For now just return nothing
diff --git a/LibZlib/CHANGELOG.md b/LibZlib/CHANGELOG.md
index f4e1642..fd4c36f 100644
--- a/LibZlib/CHANGELOG.md
+++ b/LibZlib/CHANGELOG.md
@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
-- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
+- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72) [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
 - Added support for Julia 1.6 [#68](https://github.com/JuliaIO/ChunkCodecs.jl/pull/68)
 
 ## [v0.2.1](https://github.com/JuliaIO/ChunkCodecs.jl/tree/LibZlib-v0.2.1) - 2025-07-28
diff --git a/LibZlib/src/decode.jl b/LibZlib/src/decode.jl
index 568de19..ec039b7 100644
--- a/LibZlib/src/decode.jl
+++ b/LibZlib/src/decode.jl
@@ -80,6 +80,8 @@ function GzipDecodeOptions(;
     GzipDecodeOptions(codec)
 end
 
+can_concatenate(::GzipDecodeOptions) = true
+
 const _AllDecodeOptions = Union{ZlibDecodeOptions, DeflateDecodeOptions, GzipDecodeOptions}
 
 is_thread_safe(::_AllDecodeOptions) = true
@@ -103,7 +105,7 @@ function try_resize_decode!(d::_AllDecodeOptions, dst::AbstractVector{UInt8}, sr
     end
     cconv_src = Base.cconvert(Ptr{UInt8}, src)
     # This outer loop is to decode a concatenation of multiple compressed streams.
-    # If `can_concatenate(d.codec)` is false, this outer loop doesn't rerun.
+    # If `can_concatenate(d)` is false, this outer loop doesn't rerun.
     while true
         stream = ZStream()
         inflateInit2(stream, _windowBits(d.codec))
@@ -166,8 +168,8 @@ function try_resize_decode!(d::_AllDecodeOptions, dst::AbstractVector{UInt8}, sr
                             @assert real_dst_size ∈ 0:length(dst)
                             return real_dst_size
                         else
-                            if can_concatenate(d.codec)
-                                # try and decompress next stream if the codec can_concatenate
+                            if can_concatenate(d)
+                                # try and decompress next stream if the decoder can_concatenate
                                 # there must be progress
                                 @assert stream.avail_in < start_avail_in || stream.avail_out < start_avail_out
                                 break
diff --git a/LibZstd/CHANGELOG.md b/LibZstd/CHANGELOG.md
index 8367f0c..a6bff79 100644
--- a/LibZstd/CHANGELOG.md
+++ b/LibZstd/CHANGELOG.md
@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
-- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72)
+- Update to `ChunkCodecCore` 0.6 [#72](https://github.com/JuliaIO/ChunkCodecs.jl/pull/72) [#73](https://github.com/JuliaIO/ChunkCodecs.jl/pull/73)
 - Added support for Julia 1.6 [#68](https://github.com/JuliaIO/ChunkCodecs.jl/pull/68)
 
 ## [v0.2.1](https://github.com/JuliaIO/ChunkCodecs.jl/tree/LibZstd-v0.2.1) - 2025-07-28
diff --git a/LibZstd/src/ChunkCodecLibZstd.jl b/LibZstd/src/ChunkCodecLibZstd.jl
index 9e6b602..3b90c4a 100644
--- a/LibZstd/src/ChunkCodecLibZstd.jl
+++ b/LibZstd/src/ChunkCodecLibZstd.jl
@@ -66,7 +66,6 @@ See also [`ZstdEncodeOptions`](@ref) and [`ZstdDecodeOptions`](@ref)
 struct ZstdCodec <: Codec
 end
 decode_options(::ZstdCodec) = ZstdDecodeOptions()
-can_concatenate(::ZstdCodec) = true
 
 include("encode.jl")
 include("decode.jl")
diff --git a/LibZstd/src/decode.jl b/LibZstd/src/decode.jl
index 53f5588..b29aa8b 100644
--- a/LibZstd/src/decode.jl
+++ b/LibZstd/src/decode.jl
@@ -50,6 +50,8 @@ end
 
 is_thread_safe(::ZstdDecodeOptions) = true
 
+can_concatenate(::ZstdDecodeOptions) = true
+
 # find_decompressed_size is modified from CodecZstd.jl
 # https://github.com/JuliaIO/CodecZstd.jl/blob/2f7d084b8b157d83ed85e9d15105f0a708038e45/src/libzstd.jl#L157C1-L215C4
 # From mkitti's PR https://github.com/JuliaIO/CodecZstd.jl/pull/63