Will it read
your export?
Every tool in this market asks you to install it, sign up, or upload a year of your trading history before it will tell you whether it can read your file at all. Drop the file here instead and find out first.
Input — your broker’s CSV
Ask your broker for a transaction or activity export — the list of what you bought and sold. A "realised gains" or "CGT report" export is a different thing, and this will tell you if you have brought one by mistake.
Result
Drop a file to fill this in. Nothing is uploaded — the answer is computed in this tab.
Your file is read by the same import code the desktop app uses, compiled to WebAssembly and running inside this browser tab. It is not uploaded, and there is nothing at the other end to upload it to: this site has no server that receives data, no accounts, no cookies and no analytics. You can watch the network tab while you use it.
Why this question is worth asking first
"Will it even read my file?" is the question that actually decides whether tax software is any use to you, and it is the one nobody will answer until you have committed. Broker exports differ in every way a CSV can differ — column names, date formats, whether prices are in pounds or pence, whether the direction of a trade is a word or the sign of a number, whether there is a preamble above the header.
So rather than claim a list of supported brokers and let you discover the truth afterwards, this runs the real importer on your real file and tells you what happened.
What the answer means
"Recognised"
We matched your file to a broker profile and read it. You will see how many trades and non-trade rows were found, and — where your broker states its own settled totals — how many rows we checked our arithmetic against and agreed with.
Note the flag under the platform name. Beta means that profile was written from the platform's published documentation and has never been checked against a real export. It is honest work and it usually reads the file correctly, but it is not the same claim as Validated, which means a real export from that platform is in our test suite and imports on every build. Today only Trading 212 is validated. We would rather say so than pad a supported-brokers list.
"Unrecognised — but mappable"
No profile matched. This is not a dead end, and it is the case the desktop app was designed around: the mapping wizard shows you your own columns, proposes what each one means, previews the result, and only then saves anything. The checker tells you how much of that proposal it can already fill in.
"Not a CSV we can read"
The file is not delimited text — most often an .xls/.xlsx spreadsheet or a PDF statement. Re-export as CSV, or save the spreadsheet as CSV, and try again.
A note on the wrong kind of export
Several platforms will happily give you a realised gains or CGT report. Do not use one. Its rows are disposals the broker has already matched, using a cost it pooled from acquisitions the file does not contain — and a broker can only see its own account, while HMRC pools a security across everything you hold anywhere. Forced through as trades, those rows would enter the pool a second time. If you drop one here, the checker will say so rather than let it through.
If it mentions an ISA or a SIPP
Gains inside a Stocks and Shares ISA or a SIPP are outside Capital Gains Tax entirely, so those trades should not be in a CGT calculation at all. If the words appear in your file's preamble or its name, the checker points it out — but it is a hint and nothing more. Only you know which account an export came from, which is why GainPool asks you to tag each import and then excludes what you tag.
Export we could not read, and you would like us to? Send it to hello@longstopsoftware.com and a person will look at it. Real exports are the only thing that graduates a broker profile out of beta — with a redacted file we can add support for your platform properly, and test it.
Then it can do
your whole year.
Every broker merged into one pool per security, SA108 box numbers ready to type in, and a computation pack showing the working behind every figure. £12, once.