Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


Foldseek enables fast and sensitive comparisons of large structure sets.


van Kempen M, Kim S, Tumescheit C, Mirdita M, Söding J, and Steinegger M. Foldseek: fast and accurate protein structure search. bioRxiv, doi:10.1101/2022.02.07.479398 (2022)


Search your protein structures against the AlphaFoldDB and PDB in seconds using our Foldseek webserver: 🚀


# static Linux AVX2 build (check using: cat /proc/cpuinfo | grep avx2)
wget; tar xvzf foldseek-linux-avx2.tar.gz; export PATH=$(pwd)/foldseek/bin/:$PATH
# static Linux SSE4.1 build (check using: cat /proc/cpuinfo | grep sse4_1)
wget; tar xvzf foldseek-linux-sse41.tar.gz; export PATH=$(pwd)/foldseek/bin/:$PATH
# static macOS build (universal binary with SSE4.1/AVX2/M1 NEON)
wget; tar xvzf foldseek-osx-universal.tar.gz; export PATH=$(pwd)/foldseek/bin/:$PATH
# conda installer 
conda install -c conda-forge -c bioconda foldseek

Other precompiled binaries for ARM64, PPC64LE amd SSE2 are available at

Quick start

easy-search can search single or multiple query structures formatted in PDB/mmCIF format (flat or .gz) against a target database (example/) of protein structures. It outputs a tab-separated file of the alignments (.m8) the fields are query,target,fident,alnlen,mismatch,gapopen,qstart,qend,tstart,tend,evalue,bits.

foldseek easy-search example/d1asha_ example/ aln.m8 tmpFolder

The output can be customized with the --format-output option e.g. --format-output "query,target,qaln,taln" returns the query and target accession and the pairwise alignments in tab separated format. You can choose many different output columns.

The target database can be pre-processed by createdb. This make sense if searched multiple times.

foldseek createdb example/ targetDB
foldseek easy-search example/d1asha_ targetDB aln.m8 tmpFolder

Important search parameters

# sensitivity 
-s                       adjust the sensitivity to speed trade-off.
                         lower is faster, higher more sensitive (fast: 7.5, highest sensitivity (default): 9.5)
--max-seqs               adjust the amount of prefilter that are handed to the alignment. 
                         Increasing it can lead to more hits (default: 300)
# other                         
--alignment-type         0: 3Di Gotoh-Smith-Waterman (local, not recommended), 
                         1: TMalign (global), 
                         2: 3Di+AA Gotoh-Smith-Waterman (local, default)
-c                       list matches above this fraction of aligned (covered) residues (see --cov-mode) (default: 0.0) 
--cov-mode               0: coverage of query and target, 1: coverage of target, 2: coverage of query


The databases command downloads pre-generated databases like PDB or AlphaFoldDB.

# pdb  
foldseek databases PDB100 pdb tmp 
# alphafold db
foldseek databases Alphafold/Proteome afdb tmp 

We currently support the following databases:

  Name                  Type            Taxonomy        Url
- Alphafold/Proteome    Aminoacid            yes
- Alphafold/Swiss-Prot  Aminoacid            yes
- PDB100                Aminoacid            yes

Main Modules

  • easy-search fast protein structure search
  • createdb create a database from protein structures (PDB,mmCIF, mmJSON)
  • databases download pre-assembled databases

Using TMalign for the alignment

Foldseek supports to realign hits using TMalign as well as rescoring alignments using TMscore.

foldseek easy-search example/d1asha_ example/ aln tmp --alignment-type 1

In case of the alignment type (--alignment-type 1) tmalign we sort the results by the TMscore normalized by query length. We write the TMscore into the e-value(=TMscore) as well as into the score(=TMscore*100) field.

Rescore aligments using TMscore

It is possible to compute TMscores for the kind of alignment output (e.g. 3Di/AA) using the following commands:

foldseek createdb example/ targetDB
foldseek createdb example/ queryDB
foldseek search queryDB targetDB aln tmpFolder -a
foldseek aln2tmscore queryDB targetDB aln aln_tmscore
foldseek createtsv queryDB targetDB aln_tmscore aln_tmscore.tsv

Output format aln_tmscore.tsv: query and target identifier, TMscore, translation(3) and rotation vector=(3x3)

Search result visualisations

Foldseek can locally generate a search result HTML similiar to the webserver by specifying the format mode --format-mode 3

foldseek easy-search example/d1asha_ example/ result.html tmp --format-mode 3

Cluster structures

The following command aligns the input structures all-against-all and keeps only alignments with 80% of the sequence covered by the alignment (-c 0.8) (read more about alignment coverage here). It then clusters the results using greedy set cover algorithm. The clustering mode can be adjusted using --cluster-mode, read more here. The clustering output format is described here.

foldseek createdb example/ db
foldseek search db db aln tmpFolder -c 0.8 
foldseek clust db aln clu
foldseek createtsv db db clu clu.tsv

Query centered multiple sequence alignment

Foldseek can generate a3m based multiple sequence alignments using the following commands. a3m can be converted to fasta format using ( in.a3m out.fas).

foldseek createdb example/ targetDB
foldseek createdb example/ queryDB
foldseek search queryDB targetDB aln tmpFolder -a
foldseek result2msa queryDB targetDB aln msa --msa-format-mode 6
foldseek unpackdb msa msa_output --unpack-suffix a3m --unpack-name-mode 0

Compile from source

Compiling foldseek from source has the advantage of system-specific optimizations, which should improve its performance. To compile it git, g++ (4.9 or higher) and cmake (3.0 or higher) are required. Afterwards, the foldseek binary will be located in the build/bin directory.

git clone
cd foldseek
mkdir build
cd build
make -j
make install
export PATH=$(pwd)/foldseek/bin/:$PATH

If you want to compile foldseek on macOS, please install and use gcc from Homebrew. The default macOS clang compiler does not support OpenMP (by default) and foldseek will not be able to run multi-threaded. Adjust the cmake call above to:

CC="$(brew --prefix)/bin/gcc-11" CXX="$(brew --prefix)/bin/g++-11" cmake -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=. ..