diff --git a/go.mod b/go.mod
index 8594463c..65b61f86 100644
--- a/go.mod
+++ b/go.mod
@@ -4,22 +4,26 @@ go 1.18
 
 require (
 	github.com/awalterschulze/gographviz v0.0.0-20190522210029-fa59802746ab
-	github.com/cheggaaa/mb v1.0.3
+	github.com/cespare/xxhash v1.1.0
 	github.com/goccy/go-graphviz v0.0.9
 	github.com/gogo/protobuf v1.3.2
+	github.com/huandu/skiplist v1.2.0
 	github.com/ipfs/go-cid v0.1.0
 	github.com/libp2p/go-libp2p v0.20.3
 	github.com/libp2p/go-libp2p-core v0.16.1
 	github.com/mr-tron/base58 v1.2.0
 	github.com/multiformats/go-multibase v0.0.3
 	github.com/multiformats/go-multihash v0.1.0
-	github.com/stretchr/testify v1.7.0
+	github.com/stretchr/testify v1.8.0
+	github.com/zeebo/blake3 v0.2.3
 	go.uber.org/zap v1.21.0
+	gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22
 	gopkg.in/yaml.v3 v3.0.1
 	storj.io/drpc v0.0.32
 )
 
 require (
+	github.com/OneOfOne/xxhash v1.2.8 // indirect
 	github.com/btcsuite/btcd v0.22.1 // indirect
 	github.com/btcsuite/btcd/btcec/v2 v2.1.3 // indirect
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 // indirect
@@ -27,7 +31,7 @@ require (
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
 	github.com/fogleman/gg v1.3.0 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
-	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
+	github.com/klauspost/cpuid/v2 v2.0.12 // indirect
 	github.com/libp2p/go-buffer-pool v0.0.2 // indirect
 	github.com/libp2p/go-openssl v0.0.7 // indirect
 	github.com/minio/blake2b-simd v0.0.0-20160723061019-3f5f724cb5b1 // indirect
@@ -48,7 +52,6 @@ require (
 	golang.org/x/image v0.0.0-20200119044424-58c23975cae1 // indirect
 	golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
-	gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	lukechampine.com/blake3 v1.1.6 // indirect
 )
diff --git a/go.sum b/go.sum
index 12ac3e57..6c6a5a5f 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,6 @@
+github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/OneOfOne/xxhash v1.2.8 h1:31czK/TI9sNkxIKfaUfGlU47BAxQ0ztGgd9vPyqimf8=
+github.com/OneOfOne/xxhash v1.2.8/go.mod h1:eZbhyaAYD41SGSSsnmcpxVoRiQ/MPUTjUdIIOT9Um7Q=
 github.com/awalterschulze/gographviz v0.0.0-20190522210029-fa59802746ab h1:+cdNqtOJWjvepyhxy23G7z7vmpYCoC65AP0nqi1f53s=
 github.com/awalterschulze/gographviz v0.0.0-20190522210029-fa59802746ab/go.mod h1:GEV5wmg4YquNw7v1kkyoX9etIk8yVmXj+AkDHuuETHs=
 github.com/benbjohnson/clock v1.1.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
@@ -8,8 +11,8 @@ github.com/btcsuite/btcd/btcec/v2 v2.1.3 h1:xM/n3yIhHAhHy04z4i43C8p4ehixJZMsnrVJ
 github.com/btcsuite/btcd/btcec/v2 v2.1.3/go.mod h1:ctjw4H1kknNJmRN4iP1R7bTQ+v3GJkZBd6mui8ZsAZE=
 github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 h1:q0rUy8C/TYNBQS1+CGKw68tLOFYSNEs0TFnxxnS9+4U=
 github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1/go.mod h1:7SFka0XMvUgj3hfZtydOrQY2mwhPclbT2snogU7SQQc=
-github.com/cheggaaa/mb v1.0.3 h1:03ksWum+6kHclB+kjwKMaBtgl5gtNYUwNpxsHQciKe8=
-github.com/cheggaaa/mb v1.0.3/go.mod h1:NUl0GBtFLlfg2o6iZwxzcG7Lslc2wV/ADTFbLXtVPE4=
+github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
+github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
 github.com/corona10/goimagehash v1.0.2 h1:pUfB0LnsJASMPGEZLj7tGY251vF+qLGqOgEP4rUs6kA=
 github.com/corona10/goimagehash v1.0.2/go.mod h1:/l9umBhvcHQXVtQO1V6Gp1yD20STawkhRnnX0D1bvVI=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -27,6 +30,10 @@ github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
+github.com/huandu/go-assert v1.1.5 h1:fjemmA7sSfYHJD7CUqs9qTwwfdNAx7/j2/ZlHXzNB3c=
+github.com/huandu/go-assert v1.1.5/go.mod h1:yOLvuqZwmcHIC5rIzrBhT7D3Q9c3GFnd0JrPVhn/06U=
+github.com/huandu/skiplist v1.2.0 h1:gox56QD77HzSC0w+Ws3MH3iie755GBJU1OER3h5VsYw=
+github.com/huandu/skiplist v1.2.0/go.mod h1:7v3iFjLcSAzO4fN5B8dvebvo/qsfumiLiDXMrPiHF9w=
 github.com/ipfs/go-cid v0.0.7/go.mod h1:6Ux9z5e+HpkQdckYoX1PG/6xqKspzlEIR5SDmgqgC/I=
 github.com/ipfs/go-cid v0.1.0 h1:YN33LQulcRHjfom/i25yoOZR4Telp1Hr/2RU3d0PnC0=
 github.com/ipfs/go-cid v0.1.0/go.mod h1:rH5/Xv83Rfy8Rw6xG+id3DYAMUVmem1MowoKwdXmN2o=
@@ -34,8 +41,9 @@ github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJS
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/cpuid/v2 v2.0.4/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
-github.com/klauspost/cpuid/v2 v2.0.9 h1:lgaqFMSdTdQYdZ04uHyN2d/eKdOMyi2YLSvlQIBFYa4=
 github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
+github.com/klauspost/cpuid/v2 v2.0.12 h1:p9dKCg8i4gmOxtv35DvrYoWqYzQrvEVdjQ762Y0OqZE=
+github.com/klauspost/cpuid/v2 v2.0.12/go.mod h1:g2LTdtYhdyuGPqyWyv7qRAmj1WBqxuObKfj5c0PQa7c=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -85,18 +93,28 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/spacemonkeygo/spacelog v0.0.0-20180420211403-2296661a0572 h1:RC6RW7j+1+HkWaX/Yh71Ee5ZHaHYt7ZP4sQgUrm6cDU=
 github.com/spacemonkeygo/spacelog v0.0.0-20180420211403-2296661a0572/go.mod h1:w0SWMsp6j9O/dk4/ZpIhL+3CkG8ofA2vuv7k+ltqUMc=
+github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
 github.com/spaolacci/murmur3 v1.1.0 h1:7c1g84S4BPRrfL5Xrdp6fOJ206sU9y293DDHaoy0bLI=
 github.com/spaolacci/murmur3 v1.1.0/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+github.com/zeebo/assert v1.1.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
 github.com/zeebo/assert v1.3.0 h1:g7C04CbJuIDKNPFHmsk4hwZDO5O+kntRxzaUoNXj+IQ=
+github.com/zeebo/blake3 v0.2.3 h1:TFoLXsjeXqRNFxSbk35Dk4YtszE/MQQGK10BH4ptoTg=
+github.com/zeebo/blake3 v0.2.3/go.mod h1:mjJjZpnsyIVtVgTOSpJ9vmRE4wgDeyt2HU3qXvvKCaQ=
 github.com/zeebo/errs v1.2.2 h1:5NFypMTuSdoySVTqlNs1dEoU21QVamMQJxW/Fii5O7g=
 github.com/zeebo/errs v1.2.2/go.mod h1:sgbWHsvVuTPHcqJJGQ1WhI5KbWlHYz+2+2C/LSEtCw4=
+github.com/zeebo/pcg v1.0.1 h1:lyqfGeWiv4ahac6ttHs+I5hwtH/+1mrhlCtVNQM2kHo=
+github.com/zeebo/pcg v1.0.1/go.mod h1:09F0S9iiKrwn9rlI5yjLkmrug154/YRW6KnnXVDM/l4=
 go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/atomic v1.9.0 h1:ECmE8Bn/WFTYwEW/bpKD3M8VtR/zQVbavAoalC1PYyE=
 go.uber.org/atomic v1.9.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
@@ -164,6 +182,7 @@ gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogR
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22 h1:VpOs+IwYnYBaFnrNAeB8UUWtL3vEUnzSCL1nVjPhqrw=
 gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22/go.mod h1:yeKp02qBN3iKW1OzL3MGk2IdtZzaj7SFntXj72NppTA=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
diff --git a/util/ldiff/diff.go b/util/ldiff/diff.go
new file mode 100644
index 00000000..29fa04f7
--- /dev/null
+++ b/util/ldiff/diff.go
@@ -0,0 +1,288 @@
+// Package ldiff provides a container of elements with fixed id and changeable content.
+// Diff can calculate the difference with another diff container (you can make it remote) with minimum hops and traffic.
+package ldiff
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"github.com/cespare/xxhash"
+	"github.com/huandu/skiplist"
+	"github.com/zeebo/blake3"
+	"math"
+	"sync"
+)
+
+// New creates new Diff container
+//
+// divideFactor - means how many hashes you want to ask for once
+//
+//	it must be 2 or greater
+//	normal value usually between 4 and 64
+//
+// compareThreshold - means the maximum count of elements remote diff will send directly
+//
+//	if elements under range will be more - remote diff will send only hash
+//	it must be 1 or greater
+//	normal value between 8 and 64
+//
+// Less threshold and divideFactor - less traffic but more requests
+func New(divideFactor, compareThreshold int) Diff {
+	if divideFactor < 2 {
+		divideFactor = 2
+	}
+	if compareThreshold < 1 {
+		compareThreshold = 1
+	}
+	d := &diff{
+		divideFactor:     divideFactor,
+		compareThreshold: compareThreshold,
+	}
+	d.sl = skiplist.New(d)
+	return d
+}
+
+var hashersPool = &sync.Pool{
+	New: func() any {
+		return blake3.New()
+	},
+}
+
+var ErrElementNotFound = errors.New("element not found")
+
+// Element of data
+type Element struct {
+	Id   string
+	Head string
+}
+
+// Range request to get RangeResult
+type Range struct {
+	From, To uint64
+	Limit    int
+}
+
+// RangeResult response for Range
+type RangeResult struct {
+	Hash     []byte
+	Elements []Element
+	Count    int
+}
+
+type element struct {
+	Element
+	hash uint64
+}
+
+// Diff contains elements and can compare it with Remote diff
+type Diff interface {
+	Remote
+	// Set adds or update element in container
+	Set(e Element)
+	// RemoveId removes element by id
+	RemoveId(id string) error
+	// Diff makes diff with remote container
+	Diff(ctx context.Context, dl Remote) (newIds, changedIds, removedIds []string, err error)
+}
+
+// Remote interface for using in the Diff
+type Remote interface {
+	// Ranges calculates given ranges and return results
+	Ranges(ctx context.Context, ranges []Range, resBuf []RangeResult) (results []RangeResult, err error)
+}
+
+type diff struct {
+	sl               *skiplist.SkipList
+	divideFactor     int
+	compareThreshold int
+	mu               sync.RWMutex
+}
+
+// Compare implements skiplist interface
+func (d *diff) Compare(lhs, rhs interface{}) int {
+	lhe := lhs.(*element)
+	rhe := rhs.(*element)
+	if lhe.Id == rhe.Id {
+		return 0
+	}
+	if lhe.hash > rhe.hash {
+		return 1
+	} else if lhe.hash < rhe.hash {
+		return -1
+	}
+	if lhe.Id > rhe.Id {
+		return 1
+	} else {
+		return -1
+	}
+}
+
+// CalcScore implements skiplist interface
+func (d *diff) CalcScore(key interface{}) float64 {
+	return 0
+}
+
+// Set adds or update element in container
+func (d *diff) Set(e Element) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	el := &element{Element: e, hash: xxhash.Sum64([]byte(e.Id))}
+	d.sl.Remove(el)
+	d.sl.Set(el, nil)
+}
+
+// RemoveId removes element by id
+func (d *diff) RemoveId(id string) error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	el := &element{Element: Element{
+		Id: id,
+	}, hash: xxhash.Sum64([]byte(id))}
+	if d.sl.Remove(el) == nil {
+		return ErrElementNotFound
+	}
+	return nil
+}
+
+func (d *diff) getRange(r Range) (rr RangeResult) {
+	hasher := hashersPool.Get().(*blake3.Hasher)
+	defer hashersPool.Put(hasher)
+	hasher.Reset()
+
+	el := d.sl.Find(&element{hash: r.From})
+	rr.Elements = make([]Element, 0, r.Limit)
+	var overfill bool
+	for el != nil && el.Key().(*element).hash <= r.To {
+		elem := el.Key().(*element).Element
+		el = el.Next()
+
+		hasher.WriteString(elem.Id)
+		hasher.WriteString(elem.Head)
+		rr.Count++
+		if !overfill {
+			if len(rr.Elements) < r.Limit {
+				rr.Elements = append(rr.Elements, elem)
+			}
+			if len(rr.Elements) == r.Limit && el != nil {
+				overfill = true
+			}
+		}
+	}
+	if overfill {
+		rr.Elements = nil
+	}
+	rr.Hash = hasher.Sum(nil)
+	return
+}
+
+// Ranges calculates given ranges and return results
+func (d *diff) Ranges(ctx context.Context, ranges []Range, resBuf []RangeResult) (results []RangeResult, err error) {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
+	results = resBuf[:0]
+	for _, r := range ranges {
+		results = append(results, d.getRange(r))
+	}
+	return
+}
+
+type diffCtx struct {
+	newIds, changedIds, removedIds []string
+
+	toSend, prepare []Range
+	myRes, otherRes []RangeResult
+}
+
+var errMismatched = errors.New("query and results mismatched")
+
+// Diff makes diff with remote container
+func (d *diff) Diff(ctx context.Context, dl Remote) (newIds, changedIds, removedIds []string, err error) {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
+
+	dctx := &diffCtx{}
+	dctx.toSend = append(dctx.toSend, Range{
+		From:  0,
+		To:    math.MaxUint64,
+		Limit: d.compareThreshold,
+	})
+	for len(dctx.toSend) > 0 {
+		fmt.Println("fill ranges:", len(dctx.toSend))
+		if dctx.myRes, err = d.Ranges(ctx, dctx.toSend, dctx.myRes); err != nil {
+			return
+		}
+		if dctx.otherRes, err = dl.Ranges(ctx, dctx.toSend, dctx.otherRes); err != nil {
+			return
+		}
+		if len(dctx.otherRes) != len(dctx.toSend) || len(dctx.myRes) != len(dctx.toSend) {
+			err = errMismatched
+			return
+		}
+		for i, r := range dctx.toSend {
+			d.compareResults(dctx, r, dctx.myRes[i], dctx.otherRes[i])
+		}
+		dctx.toSend, dctx.prepare = dctx.prepare, dctx.toSend
+		dctx.prepare = dctx.prepare[:0]
+	}
+	return dctx.newIds, dctx.changedIds, dctx.removedIds, nil
+}
+
+func (d *diff) compareResults(dctx *diffCtx, r Range, myRes, otherRes RangeResult) {
+	// both hash equals - do nothing
+	if bytes.Equal(myRes.Hash, otherRes.Hash) {
+		return
+	}
+
+	// both has elements
+	if len(myRes.Elements) == myRes.Count && len(otherRes.Elements) == otherRes.Count {
+		d.compareElements(dctx, myRes.Elements, otherRes.Elements)
+		return
+	}
+
+	// make more queries
+	divideFactor := uint64(d.divideFactor)
+	perRange := (r.To - r.From) / divideFactor
+	align := ((r.To-r.From)%divideFactor + 1) % divideFactor
+	if align == 0 {
+		perRange += 1
+	}
+	var j = r.From
+	for i := 0; i < d.divideFactor; i++ {
+		if i == d.divideFactor-1 {
+			perRange += align
+		}
+		dctx.prepare = append(dctx.prepare, Range{From: j, To: j + perRange - 1, Limit: r.Limit})
+		j += perRange
+	}
+	return
+}
+
+func (d *diff) compareElements(dctx *diffCtx, my, other []Element) {
+	find := func(list []Element, targetEl Element) (has, eq bool) {
+		for _, el := range list {
+			if el.Id == targetEl.Id {
+				return true, el.Head == targetEl.Head
+			}
+		}
+		return false, false
+	}
+
+	for _, el := range my {
+		has, eq := find(other, el)
+		if !has {
+			dctx.removedIds = append(dctx.removedIds, el.Id)
+			continue
+		} else {
+			if !eq {
+				dctx.changedIds = append(dctx.changedIds, el.Id)
+			}
+		}
+	}
+
+	for _, el := range other {
+		if has, _ := find(my, el); !has {
+			dctx.newIds = append(dctx.newIds, el.Id)
+		}
+	}
+}
diff --git a/util/ldiff/diff_test.go b/util/ldiff/diff_test.go
new file mode 100644
index 00000000..bf6f5e61
--- /dev/null
+++ b/util/ldiff/diff_test.go
@@ -0,0 +1,101 @@
+package ldiff
+
+import (
+	"context"
+	"fmt"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gopkg.in/mgo.v2/bson"
+	"math"
+	"testing"
+)
+
+func TestDiff_fillRange(t *testing.T) {
+	d := New(4, 4).(*diff)
+	for i := 0; i < 10; i++ {
+		el := Element{
+			Id:   fmt.Sprint(i),
+			Head: fmt.Sprint("h", i),
+		}
+		d.Set(el)
+	}
+	t.Log(d.sl.Len())
+
+	t.Run("elements", func(t *testing.T) {
+		r := Range{From: 0, To: math.MaxUint64, Limit: 10}
+		res := d.getRange(r)
+		assert.NotNil(t, res.Hash)
+		assert.Len(t, res.Elements, 10)
+	})
+	t.Run("hash", func(t *testing.T) {
+		r := Range{From: 0, To: math.MaxUint64, Limit: 9}
+		res := d.getRange(r)
+		t.Log(len(res.Elements))
+		assert.NotNil(t, res.Hash)
+		assert.Nil(t, res.Elements)
+	})
+}
+
+func TestDiff_Diff(t *testing.T) {
+	t.Run("basic", func(t *testing.T) {
+		d1 := New(16, 16)
+		d2 := New(16, 16)
+		for i := 0; i < 1000; i++ {
+			id := fmt.Sprint(i)
+			head := bson.NewObjectId().Hex()
+			d1.Set(Element{
+				Id:   id,
+				Head: head,
+			})
+			d2.Set(Element{
+				Id:   id,
+				Head: head,
+			})
+		}
+
+		ctx := context.Background()
+
+		newIds, changedIds, removedIds, err := d1.Diff(ctx, d2)
+		require.NoError(t, err)
+		assert.Len(t, newIds, 0)
+		assert.Len(t, changedIds, 0)
+		assert.Len(t, removedIds, 0)
+
+		d2.Set(Element{
+			Id:   "newD1",
+			Head: "newD1",
+		})
+		d2.Set(Element{
+			Id:   "1",
+			Head: "changed",
+		})
+		require.NoError(t, d2.RemoveId("0"))
+
+		newIds, changedIds, removedIds, err = d1.Diff(ctx, d2)
+		require.NoError(t, err)
+		assert.Len(t, newIds, 1)
+		assert.Len(t, changedIds, 1)
+		assert.Len(t, removedIds, 1)
+	})
+}
+
+func BenchmarkDiff_Ranges(b *testing.B) {
+	d := New(16, 16)
+	for i := 0; i < 10000; i++ {
+		id := fmt.Sprint(i)
+		head := bson.NewObjectId().Hex()
+		d.Set(Element{
+			Id:   id,
+			Head: head,
+		})
+	}
+	ctx := context.Background()
+	b.ResetTimer()
+	b.ReportAllocs()
+	var resBuf []RangeResult
+	var ranges = []Range{{From: 0, To: math.MaxUint64, Limit: 10}}
+	for i := 0; i < b.N; i++ {
+		d.Ranges(ctx, ranges, resBuf)
+		resBuf = resBuf[:0]
+	}
+}