diff --git a/apps/arweave/src/ar_data_root_sync.erl b/apps/arweave/src/ar_data_root_sync.erl
index 8926279c55..3fe898ebc4 100644
--- a/apps/arweave/src/ar_data_root_sync.erl
+++ b/apps/arweave/src/ar_data_root_sync.erl
@@ -155,13 +155,13 @@ sync_block_data_roots(#state{ store_id = StoreID, range_start = RangeStart,
 sync_block_data_roots(_StoreID, Cursor, RangeEnd) when Cursor >= RangeEnd ->
 	{ok, Cursor};
 sync_block_data_roots(StoreID, Cursor, RangeEnd) ->
-	{BlockStart, BlockEnd, _} = ar_block_index:get_block_bounds(Cursor),
+	{BlockStart, BlockEnd, TXRoot} = ar_block_index:get_block_bounds(Cursor),
 	Cursor2 =
 		case BlockStart >= RangeEnd of
 			true ->
 				RangeEnd;
 			false ->
-				case ar_sync_record:is_recorded(Cursor + 1, data_roots, ?DEFAULT_MODULE) of
+				case ar_data_sync:are_data_roots_synced(BlockStart, BlockEnd, TXRoot) of
 					true ->
 						BlockEnd;
 					false ->
diff --git a/apps/arweave/src/ar_data_sync.erl b/apps/arweave/src/ar_data_sync.erl
index 093d787d56..b119903d5e 100644
--- a/apps/arweave/src/ar_data_sync.erl
+++ b/apps/arweave/src/ar_data_sync.erl
@@ -3994,7 +3994,7 @@ record_chunk_cache_size_metric() ->
 %% Return {ok, {TXRoot, BlockSize, [{DataRoot, TXSize, TXStartOffset, TXPath}, ...]}}
 %% or {error, Reason}.
 get_data_roots_for_offset(Offset) ->
-	case Offset > get_disk_pool_threshold() of
+	case Offset >= get_disk_pool_threshold() of
 		true ->
 			{error, not_found};
 		false ->
diff --git a/apps/arweave/src/ar_http_iface_middleware.erl b/apps/arweave/src/ar_http_iface_middleware.erl
index fd0d5d2d72..b381936c94 100644
--- a/apps/arweave/src/ar_http_iface_middleware.erl
+++ b/apps/arweave/src/ar_http_iface_middleware.erl
@@ -552,6 +552,70 @@ handle(<<"GET">>, [<<"data_roots">>, OffsetBin], Req, _Pid) ->
 			end
 	end;
 
+%% Accept data roots for a given block offset (>= BlockStartOffset, < BlockEndOffset).
+%% Expect only entries corresponding to non-empty transactions.
+%% Expect the complete list of entries in the order they appear in the data root index,
+%% which corresponds to sorted #tx records in the block.
+%% POST /data_roots/{offset}
+handle(<<"POST">>, [<<"data_roots">>, OffsetBin], Req, Pid) ->
+	case ar_node:is_joined() of
+		false ->
+			not_joined(Req);
+		true ->
+			ok = ar_semaphore:acquire(get_data_roots, ?DEFAULT_CALL_TIMEOUT),
+			DiskPoolThreshold = ar_data_sync:get_disk_pool_threshold(),
+			ReadOffset =
+				case catch binary_to_integer(OffsetBin) of
+					{'EXIT', _} ->
+						{reply, {400, #{}, <<>>, Req}};
+					Offset when Offset >= DiskPoolThreshold ->
+						{reply, {400, #{}, jiffy:encode(#{ error => offset_above_disk_pool_threshold }), Req}};
+					Offset when Offset < 0 ->
+						{reply, {400, #{}, jiffy:encode(#{ error => negative_offset }), Req}};
+					Offset ->
+						{BlockStart, BlockEnd, ExpectedTXRoot} = ar_block_index:get_block_bounds(Offset),
+						case ar_data_sync:are_data_roots_synced(BlockStart, BlockEnd, ExpectedTXRoot) of
+							true ->
+								{reply, {200, #{}, <<>>, Req}};
+							false ->
+								{Offset, BlockStart, BlockEnd}
+						end
+				end,
+			case ReadOffset of
+				{reply, Reply} ->
+					Reply;
+				{Offset2, BlockStart2, BlockEnd2} ->
+					case read_complete_body(Req, Pid) of
+						{ok, Body, Req2} ->
+							case ar_serialize:binary_to_data_roots(Body) of
+								{ok, {TXRoot, BlockSize, Entries}} ->
+									case ar_data_root_sync:validate_data_roots(TXRoot, BlockSize, Entries, Offset2) of
+										{ok, _} ->
+											case catch ar_data_root_sync:store_data_roots_sync(
+													BlockStart2, BlockEnd2, TXRoot, Entries) of
+												ok ->
+													{200, #{}, <<>>, Req2};
+												{'EXIT', {timeout, _}} ->
+													{503, #{}, jiffy:encode(#{ error => timeout }), Req2};
+												{'EXIT', _} ->
+													{503, #{}, jiffy:encode(#{ error => timeout }), Req2};
+												{error, Reason} ->
+													{503, #{}, jiffy:encode(#{ error => Reason }), Req2}
+											end;
+										{error, Reason} ->
+											{400, #{}, jiffy:encode(#{ error => Reason }), Req2}
+									end;
+								_ ->
+									{400, #{}, jiffy:encode(#{ error => invalid_format }), Req2}
+							end;
+						{error, body_size_too_large} ->
+							{400, #{}, <<>>, Req};
+						{error, timeout} ->
+							{503, #{}, jiffy:encode(#{ error => timeout }), Req}
+					end
+			end
+	end;
+
 handle(<<"POST">>, [<<"chunk">>], Req, Pid) ->
 	Joined =
 		case ar_node:is_joined() of
diff --git a/apps/arweave/test/ar_data_roots_sync_tests.erl b/apps/arweave/test/ar_data_roots_sync_tests.erl
index dfd261685c..de1a1c46ee 100644
--- a/apps/arweave/test/ar_data_roots_sync_tests.erl
+++ b/apps/arweave/test/ar_data_roots_sync_tests.erl
@@ -15,6 +15,13 @@ data_roots_syncs_from_peer_test_() ->
 			{ar_storage_module, get_overlap, fun(_Packing) -> 0 end}],
 		fun test_data_roots_syncs_from_peer/0).
 
+post_data_roots_test_() ->
+	ar_test_node:test_with_mocked_functions([
+			{ar_block, get_consensus_window_size, fun() -> 5 end},
+			{ar_block, get_max_tx_anchor_depth, fun() -> 5 end},
+			{ar_storage_module, get_overlap, fun(_Packing) -> 0 end}],
+		fun test_post_data_roots/0).
+
 test_data_roots_syncs_from_peer() ->
 	Wallet = {_, Pub} = ar_wallet:new(),
 	[B0] = ar_weave:init([{ar_wallet:to_address(Pub), ?AR(2_000_000_000_000_000), <<>>}]),
@@ -110,6 +117,92 @@ test_data_roots_syncs_from_peer() ->
 		Blocks
 	).
 
+test_post_data_roots() ->
+	Wallet = {_, Pub} = ar_wallet:new(),
+	[B0] = ar_weave:init([{ar_wallet:to_address(Pub), ?AR(2_000_000_000_000_000), <<>>}]),
+
+	ar_test_node:start_peer(peer1, B0),
+	ar_test_node:start_peer(main, B0),
+	ar_test_node:wait_until_joined(peer1),
+	ar_test_node:wait_until_joined(main),
+	ar_test_node:disconnect_from(peer1),
+
+	%% Mine blocks with transactions with data on peer1.
+	Data = lists:map(
+		fun(_) ->
+			TXData = generate_random_txs(Wallet),
+			TXs = [TX || {TX, _} <- TXData],
+			B = ar_test_node:post_and_mine(#{ miner => peer1, await_on => peer1 }, TXs),
+			{B, TXData}
+		end,
+		lists:seq(1, 5)
+	),
+
+	%% Mine some empty blocks to push the data blocks out of the recent window.
+	{LastB, _} = lists:last(Data),
+	lists:foldl(
+		fun(_, Height) ->
+			ar_test_node:mine(peer1),
+			ar_test_node:assert_wait_until_height(peer1, Height + 1),
+			Height + 1
+		end,
+		LastB#block.height,
+		lists:seq(1, 11)
+	),
+
+	%% Now re-join main (node A) with header syncing disabled.
+	{ok, BaseConfig} = arweave_config:get_env(),
+	MainConfig = BaseConfig#config{
+		mine = false,
+		header_sync_jobs = 0
+	},
+	ar_test_node:join_on(#{ node => main, join_on => peer1, config => MainConfig }, true),
+	ar_test_node:connect_to_peer(peer1),
+	ar_test_node:wait_until_joined(main),
+	ar_test_node:assert_wait_until_height(main, LastB#block.height + 11),
+	ar_test_node:disconnect_from(peer1),
+
+	%% Verify POST /data_roots and POST /chunk for each transaction.
+	lists:foreach(
+		fun({B, TXData}) ->
+			BlockStart = B#block.weave_size - B#block.block_size,
+			case {B#block.block_size > 0, BlockStart >= ar_data_sync:get_disk_pool_threshold()} of
+				{true, true} ->
+					assert_no_data_roots(BlockStart),
+
+					%% Fetch data roots from peer1 and POST to main.
+					Peer1 = ar_test_node:peer_ip(peer1),
+					Main = ar_test_node:peer_ip(main),
+					Path = "/data_roots/" ++ integer_to_list(BlockStart),
+					{ok, {{<<"200">>, _}, _, Body, _, _}} = ar_http:req(#{ method => get, peer => Peer1, path => Path }),
+					{ok, {{<<"200">>, _}, _, <<>>, _, _}} = ar_http:req(#{ method => post, peer => Main, path => Path, body => Body }),
+
+					%% For each transaction with data, POST its chunks to main.
+					lists:foreach(
+						fun({TX, Chunks}) ->
+							case TX#tx.data_size > 0 of
+								true ->
+									Proofs = ar_test_data_sync:get_records_with_proofs(B, TX, Chunks),
+									lists:foreach(
+										fun({_, _, _, {_, Proof}}) ->
+											{ok, {{<<"200">>, _}, _, <<>>, _, _}} = ar_test_node:post_chunk(main, ar_serialize:jsonify(Proof))
+										end,
+										Proofs
+									);
+								false ->
+									ok
+							end
+						end,
+						TXData
+					);
+				_ ->
+					ok
+			end
+		end,
+		Data
+	),
+	ok.
+
 generate_random_txs(Wallet) ->
 	Coin = rand:uniform(12),
 	case Coin of